The ball stud, a kind of bolt having a spherical head, is widely used as a part of a ball joint in steering or suspension systems of automobiles. Balls and studs are subjected to a heat treatment suitable for each material, and the shear strength of the ball stud must meet the specifications of the production company. This study evaluated the shear strength of joints according to the cooling method of ball studs with resistance welding. The shear stress of water cooling showed higher stress than that of the air cooling (as-received material). However, oil cooling showed lower stress than that of the as-received. When judged by standard deviation, mean and coefficient of variation (COV) according to the arithmetic statistics, and shape parameter, scale parameter, oil cooling is suitable.