Drawing on signaling theory, this study examines the impact of co-production on theatrical movies' box office performance. We test our hypotheses using correlative factor analysis, SEM and a comprehensive dataset of 360 movies which were released in the Chinese domestic market between 2006 and 2014 and ranked top 40 on box office. Results reveal the positive relationship between co-production and box office outcomes. The indirect effect, instead of direct effect, of co-production on box office performance is mediated through other market signals. Moreover, award, the signal proven effective by American studies, are ineffective to Chinese film market, implicating the limitation of signal model suggested by research abroad.