The internet has brought deep changes to public opinion and the research. On the one hand，the internet has changed the bearing platform，the manifestation and the social influence of public opinion，which made the network public opinion became the focus of public opinion research. On the other hand，the internet has profoundly changed the academic ecology of public opinion research，attracting scholars from different disciplines such as psychology，political science and other non humanities and social sciences disciplines entered the research field. The approved research funding at the national level in recent years and relevant journal papers help us to understand how heated the research into online public opinion is in Chinese scholarship. This paper will approach this issue from a critical perspective，to reveal the deep challenges of public opinion research under the shadow of this heated research wave，including the powers that shape the credibility of online public opinion and what researchers could respond，accordingly. The paper argues that online public opinion research should 1）focus more on “group opinions” in plural sense rather than “mass opinion” in single sense and 2）apply more qualitative methods such as online ethnography rather than mainly based on quantitative methods（particularly the heated “big data” thing）.