So far the Chinese government's response has been moderate  seeking dialogue rather than sanctions.
As usual, online opinion is divided into the “pro-North Korea” nationalist and “anti-North Korea” liberal camps. However, both camps are equally unhappy with the Chinese government's overall stance on North Korea.
Matthew Gospel AAA (@马太福音AAA) who belongs to the liberal camp believes  [zh] the latest test is a slap in China's face:
[Comment: China should abandon North Korea] China has tried its best to persuade North Korea to refrain from nuclear tests. The statement that Chinese government made at the UN Security Council carried no weight. Many times, China has tried to pull North Korea back to the negotiation table. The nuclear test on the third day of the Lunar New Year has proven once again that North Korea has no respect for China and does not take China's interest into consideration. This is like a slap in the face. Is there space for persuasion? Don't let the evil mind grow.
The Maoist website Utopia, which represents extreme nationalists, issued a public statement  [zh] celebrating the successful launch of the North Korea nuclear test:
Against all the anti-revolutionary's pressure, North Korea has successfully launched its nuclear test. It reflects the ability of Kim Jung-eun  and the ruling party in leading the North Korean people and its army for building a socialist strong nation. North Korea has earned respect from the Chinese people and people who have conscience all over the world. […]
History is like a painting and mirror. 50 years ago, under the leadership of Mao Zedong , Chinese people had successfully launched its first atomic bomb test, shattering the U.S and USSR's nuclear monopoly, ensuring Chinese national security and improving China's international status. At that time, China was in a similar situation to what North Korea is presently in. […]
The current global order is siding with strong powers who have no respect for sovereignty of others. North Korea's development in satellite, missile and nuclear technology contributes to human peace and justice. North Korea's nuclear weapons represent the power of justice counteracting imperialism, whose reactionary forces and ambitions are isolating North Korea and China.
Fortunately we can find more moderate and critical opinion. For example “Tomorrow will come ” (@不会有到不了的明天) [zh] questions the location of the nuclear test:
I don't understand. Big brother China keeps giving rice and oil and money to his dirty little brothers and wipes their asses in front of the world. When North Korea picked its nuclear test spot, it chose the border area that threaten China's northeastern provinces. The fatty Kim Jung-eun keeps saying that he will destroy South Korea and capture Lee Myung-bak , why wasn't the nuclear test at the border of North and South Korea?
Blogger Cheng Tan takes a step back and wonders  [zh] why the ‘little brother’ disobeys the ‘big brother':
North Korea knows that China is now under the challenge of the global democratization movement. Domestically, it has to handle social conflict generated by corruption and the disparity between the rich and poor. The Chinese government will not have open discussion about the threat of North Korea's nuclear development with Chinese people out of fear of arousing more social discontent.
The Chinese government is caught in a dilemma — according to the principle that “China's interests comes first in diplomacy”, the Chinese government should stop North Korea for developing nuclear weapons; yet for the “CCP, stability is the first principle”, so it cannot sanction North Korea.
Some extreme nationalists believe anything anti-North Korea is against the interest of China. For example, Zhang Hongliang  [zh] (@zhanghongliang), a famous nationalist opinion leader, labelled those who opposed the North Korean nuclear test as anti-communism and anti-China  [zh]:
[Why people who are anti-communism and anti-China are against North Korea nuclear test] Although not everyone who is against North Korea's nuclear tests are anti-communism and anti-China, everyone who is anti-communism and anti-China are against North Korea's nuclear tests. On the other hand, those who support the nuclear tests are supporters of the Chinese Communist Party (CCP) and patriots. The U.S. has cut the South Sea from China by force, Japan has invaded China's Eastern Sea, but the extreme rightists are advocating for the downfall of CCP. What would happen if the CCP works with such forces?
Zhang is not happy with the Chinese government's foreign policy  [zh]:
We pointed out soon after we heard about North Korea's nuclear test that North Korea has been compelled by the U.S. to arm themselves with nuclear weapons. If China had not sided with the U.S. in cheating North Korea, would such an incident have taken place? Now that the U.S. and Japan see China and North Korea as enemies, North Korea uses nuclear weapons to strike back at the U.S. China, on the other hand, sees North Korea as enemy, this is suicide.
Zhang Hongliang and his fellows support North Korea's nuclear tests because the U.S. and Japan are against it. They don't have the Chinese people and social justice in their hearts. All they have is ideology. They are the traitors and Chinese scumbags. Shame on them.
To all the teachers and students in Minzu University: All people on earth are angry at North Korea's nuclear test. Kim and his family's evil power and abusive military action has been condemned by the whole world. However, political opportunist and an offspring of the Cultural Revolution Zhang Hongliang, who is now working in our university has become an advocator of North Korea's nuclear tests. This is a shame to our university and I hereby make a public call to “Kick Zhang Out” of our university. Retweet this to show support.
This was retweeted more than 7000 within 6 hours of being posted on February 14, 2013.