The current study combined the situational theory of publics and the theory of reasoned action to investigate the intrinsic mechanisms behind public charitable donation behaviors in China. Three models (i.e., the situational support model, the information gaining-behavioral intentions model, and the behavioral intentions-information gaining model) were compared in a sample of 512 Chinese college students. The most parsimonious information gaining-behavioral intentions model obtained by structural equation modeling (SEM) analysis was found to fit the data best. It indicates that individuals’ information gaining is firstly predicted by their problem recognition, and then predicts individuals’ behavioral intentions along with their attitudes and subjective norms. Furthermore, the relationship between subjective norms and behavioral intentions is partially mediated by information gaining. The current study reveals the theoretical mechanisms underlying public charitable donation behaviors to a certain degree, and carries a number of practical implications for promoting China’s philanthropy development in the future.