To ascertain the cause of the wear of the PTFE anti-friction layer on the chamber gate of the Three Gorges ship lift，a nonlinear finite element calculation model of the water seal of the chamber gate is established according to the actual operating conditions of the chamber gate.By simulating the water retaining and operating conditions of the chamber gate，the effects of different rubber materials and pre-compression on the maximum contact stress，positive pressure and maximum offset of the ship chamber gate water seal are calculated.The results show that the contact stress，normal stress and maximum offset of the chamber gate decrease with the decrease of the hardness of the rubber material.The lower the water head is，the higher the sensitivity of the material hardness is.The contact stress and normal pressure increase with the increase of the pre-compression.Especially in the pre-compression stage，the normal pressure of the water seal increases significantly with the increase of the pre-compression.Finally，it is proposed to slow down the wear of the water seal PTFE anti-friction layer on the chamber gate by optimizing the water seal rubber material and reducing the pre-compression.