Abstract: To calculate the welding restraint intensity of the fillet weld and ring-stiffened cylinder,the theory of cylindrical shells was used to obtain the analytical solution of the welding restraint intensity of fillet by determining the radial displacement function of even circumferentially distributed force.The results show that the welding restraint intensity was proportional to the 1.5 power of the ratio of the thickness h to the cylindrical diameter R.The effect of the ring length on the restraint intensity was determined by the geometric mean of R and h.The restraint intensity increased with the increase of the ring length.The restraint intensity reached the limit when L/(Rh)^1/2> 5,and the restraint intensity was proportional to the ring length when L/(Rh)^1/2< 2. Key words