By the Power Band Graph(PBG) method, this paper presents a computer simulation model of the multi-branch cardiovascular circulation system, which describes the blood fluid dynamic law in the cardiovacular system by the state equation. The model gives a minute description on physiological characters of cardiovascular circulation system (CVS). An integrate computer model on CVS has been established. The model can simulate physiological characters of cardiovascular circulation system and get the simulation data and the curves of CVS hemodynamics variables. The model can be used widely in the field of physiological system simulation study, medical study, and computer-aided instruction.