From a global perspective,although the protection of freedomof expression will still be a problem in many countries,the new challenge of freedom of expression in the age of Internet is that people with ability and freedom to communicate freely tend to communicate only with people they agree with . This kind of ineffective communication leads to not only some negative consequences as″debates and communication cannot help people get close to the truth,″b ut also to some serious negative ramifications as political division and social contradiction . In 2004,Ronald Dworkin delivered his concern in his writings on political division in American democracy . He also put forward his theoretical solution—″return to the common background .″However,Dworkin's solution is more like an ideal one lack of practical strategy and workable operation . This article proposes a principle of″N ew Public Forum″and expects to solve the problem on a systematic,strategic and operational level .The principle of traditional public forum considers its main goal as solving the dilemma between the valuable role of mass media and the right of individuals to express freely and effectively .Today we have to deal with another dilemma because whereas the internet improves people's capability of sending and receiving information and expressing their opinions,the effectiveness of communication itself is still being threatened . Cyberkans,a phenomenon of worldwide network Balkanization,is the linchpin in this dilemma . Cyberkans results from complex factors such as political and legal policies,business strategies of Internet product manufacturers and a more crucial one that ordinary people as consumers tend to choose the internet product to help them filter for favorable information and opinions . In the Internet era,people not only rely on information filtration,but also prefer and actively choose filtering tools . They are fond of″p ersonalized″products,which inevitably lead to information ″cocoon″a nd″D aily Me .″That is why people with different values,different preferences and different interests are easily separated and divided into different groups . Furthermore,opinions and beliefs in divided groups tend to become extreme in the process of″G roup Polarization,″ which intensifies social contradictions and affects social stability because of the lack of effective debate and communication . Malfunction of the marketplace of opinions,group polarization and tagging tendency all manifest certain kind of ineffective communication resulting from Cyberkans . There are at least two solutions for these problems .The first one is to remove all separation institutes and integrate all information into one platform .This proposal fundamentally denies the network users'c hoices and overthrows market mechanismin the Network Economy,that's whyit can only be applied to some web sites of government and other public service departments . The second solution is to establish a new kind of″P ublic Forum″for effective communication meanwhile keeping commodity market of internet working by itself . This new Public Forum Doctrine includes the test of extensity,compatibility and,the most important,efficiency . Extensity Test requires the forum to reach as many opinion groups as possible . Compatibility Test requires theforum tocontain as many different opinions as possible .Efficiency Test requires political debaters to follow certain kind of regulations to make sure debates are reasonable and yield reasonable results . Considering the actual situation in China,the traditional mainstream media has the responsibility and capability to become the platform of the new public forum .