Laser spot welding on a stainless steel plate was investigated numerically and experimentally. A numerical method was applied to predict the dimensions of fusion zone and temperature distribution in the welding process. In the numerical approach, a three-dimensional heat source equation is used to model laser beam intensity distribution, which is assumed to be a Gaussian distribution in the radial direction and exponential decay in the penetration direction. The parameters of the pulsed Nd:YAG laser spot welding include pulse energy, pulse duration, and incident angles of laser beam. Experiments were also conducted in the study. The characteristic lengths of welded spot were measured by metallographic method, and then, the dynamical behavior of the laser welding process was visualized by a high-speed video camera. Finally, the temperature variations during the laser-spot welding process were measured by an infrared pyrometer system. It is demonstrated that the numerical results by proposed model agree well with experimental observations in predicting the characteristic lengths of welded spots. From this study, it is found that weld dimensions is a strong function of incident angles of laser beam, laser energy, and pulse duration time.