In this paper, the process of pulse laser welding is used for the tantalum sheet with a thickness of 0.5 mm.The influence of laser welding parameters on weld depth and weld width of butt joint is analyzed by orthogonal test. The results show that the depth and width increase with the increase of laser power,and the increase of melting depth is higher than that of melting width. When the power reaches 1 100 W, the weld is completely penetrated. With the increase of welding speed, the weld penetration depth decreases correspondingly. When the welding speed is greater than 8 mm/s, the rate of penetration depth decrease increases obviously. It shows that pulse width and frequency are important factors affecting welding quality. The tensile test results show that the fracture site is in the heat-affected area and the tensile strength of the joint is as same as that of the base metal. The joint has good plasticity and the welding quality meets the technological requirements. The optimal welding process parameters are power 1 200 W, defocusing capacity 0, gun tilt Angle 15°, pulse width 25 ms, frequency 20 Hz, the welding method is pulse welding, shielding gas argon, gas flow rate 10 L/min.