In financial markets, many securities have begun providing online trading services for customers to improve the efficiency of the trading process. This study explores the quality of securities brokers’ online trading Web sites and their relationships with the acceptance intentions of users in mainland China and Taiwan. Based on the Technology Acceptance Model (TAM), this study selects Web site quality (system, information, and service) as an external variable and conducts multiple regression models to test the hypotheses. Based on a total of 207 and 236 questionnaires received from mainland China and Taiwan, respectively, 151 and 204 questionnaires, respectively, were valid. The results demonstrate that Web site quality (system, information, and service) positively affects perceived usefulness and perceived ease of use, both of which are key factors in predicting users’ attitudes towards usage. These attitudes can significantly affect users’ behavioral intentions to utilize broker Web sites in mainland China and Taiwan.