In order to apply the face specific pressure accurately in the install or repair process of mechanical seal, the relationship of face specific pressure and deformation of the mechanical seal was studied.ANSYS was used to establish the finite element model of the rubber float ring of a mechanical sealBy applying different contact press on the contact surface of the float ring, the deformation at different nodes of the contact surface and along the radial direction of the contact surface was analyzed.The results show that, in the Mooney-Rivlin model, the ratio of material constants C2/C1 has little effect on displacement deformation of rubber ringWith the increasing of rubber ring radius, the increment of deformation of the contact surface is reduced.The relationship expression of face specific pressure and deformation was fitted by using the least square method, which can be used to transform the face specific pressure into intuitive displacement during the design phase of mechanical seal.The location of floating ring was determined by the displacement, and theoretical guidance was provided for the subsequent installation and maintenance.