Hydraulic differential spiral is one of key components in horizontal spiral discharge filtering centrifuge. Hydraulic differential spiral applied hydraulic pressure technology to the traditional differential, its structure is simple transfer torque differential speed large and stepless adjustable of differential speed, and can fully improve effective carrying out of centrifuge working torque. The force bearing relationship between differential plunger components during operation was analyzed, and at the same time, through the threedimensional (3D) modeling software UG, differential geometric model was established. The geometric model was gridded in hexahedral by using Hypermesh, through contact guide to establish the contact between the piston components to implement the discrete grid connection between different components. Based on the extended Lagrange algorithm, the contact nonlinear analysis was carried out on the piston components for obtaining the stress nephogram and path of the component diagram. It is concluded that the contact stress at near the dead center is the largest and contact area is in line with the Hertz contact theory, which provide theoretical basis for further research of hydraulic differential service life.