In order to calculate the wear loss of the mechanical seal of hydraulic piston pump,one method was presented to calculate the wear of mechanical seal considering the contamination level and running conditions based on the finite element model.Firstly,the finite element model of mechanical seal surface was established for a single abrasive model,and the simulation was carried out based on the actual working condition.Then the regression analysis of simulation and experimental data was carried out to determine the amount of wear caused by a single abrasive particle.Finally,the comprehensive effect of multiple particles in the medium on the wear of the mechanical seal surface was studied,and a calculation method for the wear loss of the mechanical seal used in hydraulic piston pump was proposed considering the oil contamination level.The real wear loss is obtained by observation of the seal surface.By comparing the calculated results with the observed results,it is proved that the presented method can effectively calculate the wear loss of moving pairs with lubricating contaminated.