Abstract: Three dimensional numerical simulations are conducted to study the fluid dynamics and structural mechanics of the progressive cavity pump (PCP). The influences of lifted-fluid pressure are analyzed, and a new mechanism for the slippage and abrasion of PCP is presented. The computational fluid dynamics model of the connected cavity is constructed, and the finite volume method is employed to compute the pressure distribution in the cavity. The pressure on the rotor is further obtained. A three-dimensional finite element model is also constructed to simulate the contact and interaction between the stator and rotor, with the forces and torques acting on the rotor by cavity pressure. The stress and strain states of the stator are investigated. The results indicate that the force on the rotor is the main cause of slippage, while the torque on the rotor is the main cause of abrasion at the top and bottom of the stator.