Entrepreneurs on crowdfunding platforms are increasingly using third-party endorsement. Previous literature has mainly focused on reward based crowdfunding platforms and found that third-party endorsement can help increase crowdfunding performance. However, in the pro-social context, investors are not only interested in financial returns, but also in creating social impact (i.e. obtaining altruistic returns for helping others). Therefore, third-party endorsement may have different impacts on the financial and altruistic motivations of backers, leading to the impact of third-party endorsement on crowdfunding performance. We combine theoretical and empirical models to study the impact mechanism of third-party endorsement on crowdfunding performance. Firstly, a theoretical model is constructed to analyze the decision problem of third-party endorsement for creators, taking into account the financial and altruistic motivations of backers, and hypotheses that can be empirically tested are generated. Then, empirical testing of these hypotheses was conducted using real data of a lend-based pro-social crowdfunding platform Kiva. The research results indicate that it is usually better for creators to choose third-party authentication, and its impact mechanism is as follows: third-party endorsement increases the financial motivation of backers and reduces their altruistic motivation. The financial motivation has a positive impact on crowdfunding performance, while the altruistic motivation has a negative impact on crowdfunding performance. In addition, when crowdfunding projects have higher financial (quality) signals and lower altruistic signals, the possibility of creators choosing third-party endorsement is higher.