This paper described a basic study of the pulse shaping effects on weld dimension and weld discontinuties in the continuous seam welds of STS 310S using Nd:YAG laser. Further. laser weldability tests for STS 310S and Inconel 600 was carried out. Pulse shapes used in this experiment were general type, which has been applied generally in laser material processing, ramped-up type (3 steps) and ramped--down type (3 steps). The pulse energy was constant regardless of types of pulse shape. The penetration of laser welds became deeper as the pulse width was longer and he peak power was increased. The pulse of ramped-up type was most effective for deep penetration compared with others. With regard to the laser weldability and reduction of weld discontinuties such as porosity and hot cracking, the general type pulse was the worst and the ramped-down type pulse was the best among 3 types of pulse shape studied in this investigation.