The virtuality and concealment of platformmediated network market enable sellers to hide and cheat consumers more conveniently, which leads to new governance problems. Based on transaction cost theory and social exchange theory, focusing on the perspective of platform active governance, this paper explored the influence of sellers regulation mechanism, transaction security mechanism and dispute settlement mechanism on the strong and weak speculation, and the moderating effect of platform reputation. The questionnaire survey was used to collect data from the perspective of consumers. Structural equation modeling and hierarchical regression analysis were used to analyze the data. The results show that weak speculation has a significant positive impact on strong speculation. Seller regulation mechanism and dispute settlement mechanism both have inhibitory effect on strong and weak speculation. Transaction security mechanism has positive impact on weak speculation. Platform reputation has a negative moderating effect on the relationship between transaction security mechanism, dispute settlement mechanism and weak speculation.