The simulation model of piloted relief valve was established by using AMESim based on the working principle of the valve. The study of piloted relief valve was conducted with multiple parameters as the dependent variable. The laws between all parameters and the pressure and the quantity of flow were obtained. The results show that damping hole diameter, spring stiffness and the overflow port diameter are determined as the key factors which influenced the performance of piloted relief valve. The method provides the reference for the optimal design of the structure of piloted relief valve, and is helpful for doing the similar valve characteristic experiments.