The related geometrical parameters were obtained by taking M8 valve from Rexroth as an investigation object and carrying out its measurement. Minimum flow areas of the semicircular and U shaped notches of the M8 valve were deduced, and the corresponding function expression was programmed by Matlab. When the throttling groove geometric parameters of M8 valve P-A port were inputted into the function expression programmed by Matlab, the indicatrix of the overflow areas of semicircular and U shaped notches was obtained. Meanwhile, the working theory of M8 valve was analyzed, and AMESim HCD model was set up according to this theory. Three M8 valves were used to control the excavator boom, dipper and bucket cylinder of excavator working device respectively, and the corresponding AMESim HCD simulation model was also set up. The relevant parameters of a large excavator from one enterprise were set as the parameters for the simulation model. By employing the simulation, the relevant of hydraulic components of the working device of pressure and the flow related parameters of the model were obtained. The pressure of boom cylinder, flow and the relevant of parameters curve were obtained. At last, the measured data and simulation results are compared, which results suggesting that the method above is feasible.