Abstract: Based on the verification of the validity of finite element computation for small Tekken displacement with loading-block through proving trial,small Tekken restrain computofion is conducted.The results show that the restraint is maximum at both ends of the weld,and is minimum in the middle.The restraint falling amplitude is great at both ends of the weld in a range of 5mm,and is gentle in the middle in a range of 70mm.As for different thickness of small Tekken,the thicker the greater the restraint is at the same position of small Tekken.