In order to investigate the deformation and strength of double packers in deep water test under closed annulus pressure variation,a mechanical analysis model of double packer rubber tube structure was established.According to the packers closed annulus pressure variation during the working process,the sealing performance of the rubber tube was analyzed,and the strain,equivalent stress and contact stress of each rubber tube were obtained.The contact characteristics of the packer rubber tube and casing at different circular chamfer parameters of the tube were analyzed,the influence of the tube chamfer parameters on the sealing performance of the packer was studied,and the optimized structural parameters of the packer were obtained.The results show that the strain,equivalent stress,and contact stress of each rubber cylinder all increase with the increase of the closed annulus pressure,and the increase of the lower rubber cylinder is the most significant.With the increase of circular chamfer,there is no significant change in the deformation of each rubber tube,but the equivalent stress decreases.As the circular chamfer increases,the contact stress of the upper rubber tube and the middle rubber tube increases,while the contact stress of the lower rubber tube increases first and then decreases.The conclusion shows that the increase of chamfer is beneficial to the sealing performance of the packer,and the structure is optimal when chamfer radius is 0.75 mm.