In order to improve the sealing performance of the packer,a new type of sealing structure was designed,which consisted of a radial symmetrical trapezoid spacer and a grooved rubber.The working condition of the packer was simulate by the finite element analysis method to analyze the influence of the characteristic parameters of ladder shaped spacer ring on the sealing performance of packer.The distribution rule of contact stress between rubber and casing wall with different characteristic parameters of ladder shaped spacer ring was obtained，and the structural parameters of the new seal structure were optimized.The results show that the maximum contact stress of the new sealing structure improved by 84% compared than the conventional sealing structure,when the distance between the center of the ladder ring and the end face of the spacer ring is 10 mm,the height of the bottom of trapezoid spacer ring is 9 mm,the height of the top of the ladder ring is 8 mm,the trapezoidal spacer height is 9 mm.The contact stress between the rubber and the casing wall of the new sealing structure is significantly higher than that of the conventional packer,and the sealing performance of the packer is improved.