Abstract: This paper studies the effect of consequent post heat treatment on the mechanical property and shape memory ratio Of the welded TiNi joints in TiNi shape memory alloy Precise pulse resistance butt welding, analyzes the joint structures and fractographies affecting mechanical property and shape memory ratio of welded joint by using strength testing, SEM and TEM, gets the optimum welding parameters obtaining good shape recovery ratio welded joint, and has discovered the inherent reason for proper consequent post heat treatment to promote the joint shape recovery ratio from microcosmic point. This is a base to exploit and develop TiNi shape memory alloy, and has great theoretical and practical values.