Abstract: Welding was carried out on marine 5083 spherical flat aluminum by process 1 of V-groove and higher interlayer temperature and process 2 of V(webs) + X(panel) groove and lower interlayer temperature, and the effects of the two processes on the mechanical properties of butt welded joints were studied. The results showed that the internal quality and mechanical properties of the welded joint obtained by process 2 were better than those by process 1. The groove size of process 1 was large, so the feeding amount of welding wire was large, the welding passes increased. Besides, the welding was continuous. The above reasons led to high inter layer temperature, large amount of accumulated heat and the overheating of the welding test plate. The heat made the volume of the welding pool become large, and the liquid aluminum in the pool failed to solidify in sequence during solidification, thus forming loose structure. Process 2 could inhibited the formation of loose defects in the weld and improve the mechanical properties of the joint.