When the progressive cavity pump works,the stator expands and swells under the action of high-temperature medium,which makes the stator brittle and expand,and reduces the sealing performance of the progressive cavity pump.The volumetric thermal expansion coefficient and swelling parameters of rubber materials in oil immersion and water immersion were measured through experiments,and the expression of free expansion deformation of rubber stator was deduced.The finite element calculation of stator thermal expansion deformation was carried out,and the temperature equivalent method was used to analyze the stator swelling characteristics.The deformation law of the profile by coupling thermal expansion and swelling was obtained by finite element calculation of coupled thermal expansion and swelling load.The results show that when the thermal expansion and swelling deformation of the stator occurs,the surface deformation in the stator cavity is proportional to the wall thickness,and the maximum deformation occurs at the contact position of the stator and rotor.The deformation caused by swelling is much higher than that caused by thermal expansion.The sealing characteristics of progressive cavity pump were analyzed by finite element method,and the variation law of contact stress of sealing belt between stator and rotor with temperature and interference was obtained.The results show that the contact stress increases with the increase of temperature and interference,and the maximum contact stress in oil immersion is higher than that in water immersion.