The pulsed laser welding experiment of Hastelloy C-276 of 0.5 mm thickness is conducted. According to buoyancy force and Marangoni convection, the influences of pulse duration, pulse energy, pulse repetition rate and welding velocity on weld joint are investigated. It is indicated that the pulse energy and welding velocity present the same impact on the forming of weld joint, and suitable parameters can affect the interaction between buoyancy effect and Marangoni convection. The pulse duration can decide the pool liquid flow, and further significantly impact the forming of weld joint. In addition, the variation of repetition rate determines the relative thermal action and impacts the pool flow, and finally varies the weld joint.