By using large general finite element software ABAQUS as a simulation analysis tool in this paper,based on the double ellipsoidal heat source applied in DFLUX subroutine, the process of internal and external three wire longitudinal submerged arc welding of X90M steel plate is simulated through indirect coupling method and “birth-death element” algorithm,and the welding temperature field and residual stress field are obtained.The results show that when the welding process parameters of internal and external multi wire longitudinal submerged arc welding are certain,the initial welding time (or wire spacing) of each wire determine whether to form a common weld pool; the peak temperature of multi wire eutectic pool welding is higher than that of single wire pool welding due to the severe superposition of multi heat source temperature field，the higher welding temperature field makes the metallurgical reaction in the welding process more fully, and can effectively reduce the cooling rate of the welded joint and its vicinity, resulting in the welded joint formed by multi wire eutectic pool welding has smaller residual stress.On the premise of considering both quality and production efficiency, the multi wire eutectic pool welding process is recommended in the production practice of X90M multi wire longitudinal submerged arc welding.