Recent studies show that the number of mobile devices has already exceeded the number of personal computers. Contradictorily, the commerce conducted via the mobile devices ("M-Commerce") is far less than that of internet ("E-Commerce"). This paper looks into the context of the mobile commerce from two dimensions. (i) The framework of mobile payment system, the mobile payment model, the classification of mobile payment and mobile service. Spinning out from these discussions, it helps to provide a better understanding of how the mobile payment model is constructed and what m-commerce is all about. (ii) From the user's perspective, the user acceptance analysis of the mobile users and the mobile commerce system, in which the characteristic of the users, the constraints of the system are discussed. With these two dimensions in mind, the application scenarios of the m-commerce system, that is, the situations where m-commerce can put forth to perform required task, are suggested. Our empirical results show that although people in Macau think using mobile phone is an innovative and convenient tool for making payment, the acceptance level is still not very high.