The hub dynamic seal of propeller hub adopts an O-ring seal,and its actual clearance directly changes the compression rate,which has an impact on the sealing performance. The actual clearance of the seal face of the hub was analyzed from the design and working point of view. The clearance caused by assembly error,actual working conditions and friction and wear in service was systematically studied. Based on the actual clearance,a finite element model of the dynamic seal of the hub was established in ABAQUS software. The sealing performances of the dynamic seal under different compression ratios and oil pressures were analyzed such as Mises stress,grease film thickness and pressure,and the changing rule of hub dynamic sealing performance under different clearance was revealed. The results show that as the compression ratios increases,the maximum Von-Mises stress and the maximum oil film pressure are increased,the minimum oil film thickness is slightly decreased,and the maximum Von-Mises stress gradually moves from the main contact area between the O-ring and the blade flange and the side wall of the hub body to the main contact area. As the medium pressure increases, the maximum Von-Mises stress and the maximum oil film pressure are increased,the minimum oil film thickness is slightly decreased,and the maximum Von-Mises stress gradually moves from the main contact area between the O-ring and the blade flange and the bottom of the hub body to the low pressure contact area of the flange. The maximum oil film pressure is always greater than the oil pressure value,so the dynamic seal will not fail. By properly increasing the assembly gap and medium pressure,the sealing ring can obtain better sealing performance under the self-sealing.