The reaction and regulation mechanisms of biochemical reaction system in vivo have been recognized to be very complicated and most of these are remained unsolved. For the elucidation of reaction system in vivo numerous computation works would be required. In this connection, the simulation with computer graphics on the activation of pepsinogen and the lysozyme-inhibitor interaction as model reaction systems were attempted in expectation of the saving of turn-around time in digital computation. The results clearly show that this method is the most useful one for the analysis of biochemical system with respect to the speed-up of the computation work.