Union of journalists is an informal, grass-roots collaboration, which is different from official organizations such as Journalists’ Association. It is not a unique phenomenon. Before the rise of social media, resource sharing and cooperation between journalists was mainly based on friendship.However, the scales, forms and trust of cooperation were limited so that it was difficult forit to become a regular part of news production and to form a community based on career and class. The advent of social media has just broken through these limits: the online communication between peers becomes part of everyday life; the gapsbetween journalists and institutional management becomes deeper and deeper; the boundaries between journalists and other social professionals becomes more and more obvious;journalitic professional identities and class identities became stronger and stronger. By investigating the Wechat group, we could get the first hand experience that the union of journalists based on professional community and class community have seemingly improved the efficiency of news production.However, there were some ethical issues, such as the populism tendency in the whole group, the shock to authenticity of news, and the betrayal of organizational ethics.