Mobile devices usually have too limited and expensive communication capacity to meet consistent connection requirement of online payment protocols such as SET. Mobile agent approaches have been proposed by SET/A and SET/A+ to solve the problem. In this paper, we propose a new secure agent-mediated payment scheme which provides simpler and more compatible solution. Its particular features lie at: (1) the payment procedure is combined with brokering stage during the internet trading. (2) there is no modification to the SET protocol which results in 100 percent compatibility. Moreover, system simplification can be achieved in the proposed scheme without any sacrifice of security.