Based on the theory of laser transmission welding, the feasibility of laser welding the polycarbonate (PC) sheet plastics is researched. The experimental scheme for laser transmission welding is plotted, which includes the selection of laser equipment and welding materials. Metallographic microscopy is conducted for experimental samples in order to investigate the influence of welding parameters on welding quality. Orthogonal experiment method is used to study the welding results under different conditions of laser power, welding speed and the content of carbon black in polycarbonate. The results show that the laser power is the primary influencing factor, followed by the welding speed, and the last is the content of carbon black.