To improve the noise characteristic of hydraulic relief valve widely used in practice, a 3D model of initial flow field was established according to the practical structure and parameters of a main poppet valve. By using the computational fluid dynamics(CFD) software Flue nt, numerical simulations and visual analysis of the hydraulic relief valve in d ifferent work conditions were carried out. The pressure and velocity distributi on g raphs in the valve were obtained. Based on the visual analysis, the structure a nd parameters of the valve were adjusted. Three different structure valves were co mp ared and investigated. The results show that the eddy area is reduced and the lo west pressure increases through improving the original structure, so the possib i lity to cause cavitation and noise is reduced. The study provides a basis for th e optimal design of the valve structure and parameter．