An emergency evacuation simulation model was constructed on the basis of cellular automata theory, and the corresponding visual simulation program was developed by using Visual Basic6.0. In order to simplify the algorithm in the implementation of evacuation simulation, walls and obstacles were used to divide the complex building plane into convex polygon regions, and then, doorways were used to link those regions to form a whole evacuation space. The program can be used for the evacuation simulation of buildings to figure out the critical number of occupants evacuated when serous congestion happens, so as to verify whether building layout satisfies the requirement of safety design standards, and therefore to improve the building layout.