As a recently emerged information service on the Chinese Internet, online public opinion analysis (网络舆情分析) is a type of service to monitor, assess, and synthesize online public communication through automated software and trained individuals. This article provides an industry overview of the rise of online public opinion in China and examines the political economy of the People's Public Opinion Office. Second, this article looks at the marketing of the profession in news coverage, training materials, as well as published interviews with People's Public Opinion Office's managers and experts. Through a close reading of People's Public Opinion Office's published annual reports from 2007 to 2016 focusing on the issue of online rumor, this article delineates how the identification and prognostics of online rumor evolves with the State's anti-rumor campaign that aims to forestall or pacify collective action. In sum, this article sets to examine the professionalization and industrialization of online public opinion analysis as a part of the coevolutionary dynamics between the state and civil society in China. Using the government's anti-rumor campaign as an example, this article critically investigates the mediating role online public opinion analysis plays in the "sausage factory" of public opinion gauging and monitoring, which sets the basis upon which policymaking process is guided and justified.