The official Xinhua news agency has reported that growing numbers of providers have joined what is described as a "self-discipline" scheme.
China internet facts
Second biggest online population, after US
56 million people log on from home
Internet use growing by 6% a month
Access to some foreign websites is already blocked in China and last month the authorities announced plans to close down thousands of unlicensed internet cafes.
The government says the move was prompted by a fatal fire at a cafe in Beijing, but critics argue it is an excuse to impose further controls on the use of the net.
Under the "self-discipline" scheme, the ISPs promise to stop the spread of material on the internet thought harmful to social and political stability.
'Civilised' web use
According to Xinhua, the scheme is designed to "prevent cyber crime, the spread of harmful information and unhealthy competition".
It also bans ISPs from publishing material "harmful to national security and social stability" or "in violation of the law".
The ISPs are also required to promote the "civilised" use of the web and the avoidance of breaches of intellectual property rights.
Correspondents say the Chinese Government has long had an ambiguous attitude towards the rapid growth of internet use.
Beijing is aware that a technologically advanced population is good economically, but it is very nervous about allowing its population access to un-mediated information and news.
The Chinese are now the second biggest internet users in the world, after the United States.
Last year more than 56 million of them logged on from home, and that number is growing by 6% a month.
BBC Beijing correspondent Rupert Wingfield-Hayes says the internet is changing Chinese society profoundly, breaking down the stranglehold on information held by the communist rulers.