Aimed at the increasingly harsh environment of oil and gas wells,on the basis of the sealing mechanism for premium connection,a double primary sealing structure consisted of conical surface to conical surface and cylindrical surface to spherical surface was proposed.The changes of contact stress and contact length along the primary sealing surface of three main seal structure forms(double primary sealing structure,cone/cone sealing structure and cylinder/sphere sealing structure)were analyzed by finite element method at the conditions of makeup,tension,compression,tension and internal pressure,tension and internal and external pressure.The changing laws of sealing ability of three kinds of sealing structure with load were obtained.The analysis results indicate that conical surface and cylindrical surface of the double main sealing connection show the more uniform contact stress,the longer contact length and the smaller peak contact stress under different load conditions compared with single main sealing connections.The fullscale test results show that the sealing performance of the double main sealing connection meets the application requirements.