Abstract: A new type of inverter of resistance seam welding power supply was developed for precision welding in device packaging.The main power circuit, control circuit and control software are briefly introduced, and the special current waveform designed for precision welding is introduced in detail.Experiments show that the current waveform can be set flexibly and the parameters such as current and time can be controlled accurately.The actual use for parallel seam welding of crystal oscillator shows that the power source can meet the requirements of high-quality welding, which is an ideal precision seam welding power source for fine scale parts.