Abstract: In order to study the impact of supplier encroachment on product anti-counterfeiting governance in online platform sales, a Stackelberg game model is established to analyze and compare the anti-counterfeiting governance decisions of online platforms with and without supplier encroachment. Results show that there exists a range of commission ratios such that supplier encroachment promotes the strength of anti-counterfeiting governance of a platform. In addition, the profits of resale mode suppliers and platform providers before and after the establishment of the anti-counterfeiting mechanism mainly depend on the influence of the penetration rate of counterfeit goods and the impact of quality differences. The anti-counterfeiting credibility of suppliers in establishing anti-counterfeiting mechanisms is affected by the ratio of platform rent and the proportion of resale modes in the market with supplier encroachment. Also, the anti-counterfeiting credibility is inversely proportional to the platform commission ratio and the proportion of the resale modes. Furthermore, choosing to establish an anti-counterfeiting mechanism can increase the total profit of a supply chain under certain conditions.