During laser welding high silicon aluminum (50% Si) with lid (27% Si), the welded joint crack is often found in the production process. An improved laser welding process with preheating, welding, and post-treating is described in this paper. By analyzing the relation between the process parameters of laser welding and the microstructure of welded joint，the qualified structure of welded joint without crack is obtained, which passes the reliability verification and has be used in the space hybrid microcircuit production. The yield is also greatly improved accordingly.