The research aimed to investigate 1) the factors influencing Chinese customers' trust and purchasing probability of group buying websites; 2) the differences of trust on B2C and group buying websites; and 3) whether the Theory of Reasoned Action and Gefen's summarization of trust antecedents applicable for Chinese group buying websites. The study consisted of three phases: 1) a pre-questionnaire about general trust on B2C and group buying websites; 2) an in-lab experiment following by a post-questionnaire after each trust situation; 3) a short open interview. According to the results, 1) Cognition-Based Antecedent trust is the most important factor influencing Chinese customers' trusts and purchasing probabilities of both B2C and group buying websites. 2) Participants show significantly lower general Trust Beliefs and Trust Intends on group buying websites. However, under the same trust situation, participants show significantly higher purchasing probabilities on group buying websites. 3) The Theory of Reasoned Action and Gefen's summarization of trust antecedents are not applicable for current Chinese group buying. Some implications for group buying websites were discussed.