ABAQUS software was used to carry out the step seal finite element simulation analysis about the effect of unloading angle on the sealing performance.Based on uniaxial tension compression test for rubber and plastic material stress-strain curve to define material properties,by establishing three analysis steps of initial contact,interference assembly and direct fluid pressure loading to simulate the real working conditions of the step seal,the stress-strain nephogram and the contact pressure distribution diagram of the sealing surface with and without unloading angle under different fluid pressure loads were obtained.The axial force,friction were calculated to study the effect of unloading angle.The results show that the existence of the unloading angle can obviously improve the deformation state of the step seal plastic ring,so that the waist of the plastic ring will not sag inward,but an tilt towards the direction of the unloading angle.The existence of the unloading angle will make the friction of the step seal become smaller,which plays a positive role in improving the sealing performance,reducing the mechanical loss and prolonging the service life.