Abstract:Required fluid amount test of the brake caliper is a very important part in the performance test of the brake caliper, the research on dynamic required fluid amount test only stay in the stage of test statistics at present. It cannot diagnose the fault of brake caliper. To solve the problem, the AMEsim simulation model was built on the basis of the mathematical model of the dynamic required fluid amount test system of the displacement difference method of the master cylinder, the factors of master cylinder piston speed and caliper body structure were analyzed, and the model was verified by experiments. The results show that, the speed of master cylinder piston has small effect on dynamic required fluid amount test; the return spring stiffness, the brake clearance, the friction block and the hardness of rubber seal ring have different degrees of effect on dynamic required fluid amount test, it can diagnose the fault of brake caliper according to the feature of curves.