Abstract: In order to study the variation of welding residual stresses of cone-cylinder pressure shell structures under different internal pressure, first a calculation program of welding residual stresses is accomplished with APDL of ANSYS, and its reliability is validated by a test. Based on the agreement of numerical simulation and the test, the initial welding residual stresses of the cone-cylinder pressure shell structure are calculated. Then the variation regularity of the welding residual stresses of the cone-cylinder pressure shell structure under different internal pressure is analyzed. It is obtained that the inner shell surface welding residual stresses decrease with the increasing of the internal pressure. At last, the relation of the maximum residual stresses of inner shell and the internal pressure in a certain pressure range is deduced.