Recent research on software agent is mainly based on rational agent theories that have been presented by Bratman and its core is to build BDI models for agent. But the models can not present the active cognitive processes of agent, and it is hard to richly present the relations between agent problem solving and agent mental states. Because it is not easy to build the explicit corresponding relations between the theory model and the model structure, agent rational models are difficult to realize. This paper introduces a psychologically recognized model-PASS (planning, attention, simultaneous processing and successive processing) into the study about intelligent agent, builds a new agent model named as PASS-BDI, describes the mental states, cognitive processes and whole behaviors with pi-calculus at length and strengthens the active cognitive attributes of agent. Because having built the explicit corresponding relations between this theory model and the model structure, it is easy to program in AOP practice. An application of the model in MAS is presented at last.