To study the influence of structure parameters on the sealing performance of U shaped metal sealing ring,ABAQUS was used to establish the two dimensional axisymmetric finite element model of the metal sealing U ring. Influence on the max Von Mises stress, the size and distribution of the contact pressure and the contact width under normal temperature and in working condition resulted from changes of structure parameters such as the thickness,section width, leg thickness and arc radius, were analyzed. The results show that the sealing performance is improved by increasing the thickness of original U shaped sealing ring to 38 mm or reducing the leg thickness to 01 mm, and good sealing performance are achieved when keeping values of the section width between 64 mm and 68 mm and the arc radius between 07 mm and 09 mm. In the light of warping problem of the legs of the U shaped sealing ring after loading, an improvement method that reduces the right leg height of the U shaped sealing ring is proposed according to the calculation results.