Agent architecture is an important topic in the current research of Agent. Based on BDI model and situation calculus, an Agent architecture called AASC (Agent architecture based on situation calculus), which can depict various features, especially autonomy of Agent, is presented in this paper. Since AASC provides the facilities for representing mental states of Agent, such as belief, goal, strategy and so on, reasoning about action and planning, it can serve as a uniform platform for interpreting the autonomy of Agent and constructing various types Agents.