Abstract: In order to control the grain size in nickel-based alloy weld, the effect of welding parameters on the grain size in the weld was studied. Pulse tungsten inert gas (P-TIG) welding of Inconel601H nickel-based alloy was carried out. With optical microscope, the microstructure of the weld was observed and the grain size was calculated. The results show that the effect of welding parameters on grain size of the weld was different during P-TIG of Inconel601H nickel-based alloy. With increase of peak welding current, pulse frequency and pulse duty in a certain range, the grain refinement was obvious. However, the grain tended to grow with the increase of base welding current. Therefore, the grain coarsening in nickel-based alloy weld can be improved using proper welding parameters.