Based on the ISO 13679 and the theory of the sealing capacity,the Series A full envelope load test evaluation of a premium connection was carried out at high temperature and ambient temperature with the help of finite element software,and the sealing performance of the premium connection in service conditions was analyzed.Based on the theory of the sealing capacity,the change rules of the sealing energy and the sealing energy multiple of the premium connection after the circulation of different equivalent full envelope loads,and the key factor of the sealing ability was compared and analyzed.The results show that premium connection are sensitive to high temperature(180 ℃) and 95%VME(equivalent stress level) load cycles at ambient temperature,and the average plastic strain on sealing surface is the key factor influencing the sealing ability.Both the contact pressure and the contact length decrease during a period of cycle,but the premium connection can still maintain good sealing ability.The finite element analysis method can effectively simulate the loading conditions of the ISO 13679 Series A full envelope load test,and the sealing performance simulation results are consistent with the actual test results.This method can improve the development efficiency of the premium connection,and it’s feasible to replace the full scale tests.