A new high-quality, high-efficient and low consumption welding method with nonconsumable electrode is put forward,and a high frequency hybrid twin tungsten electrode TIG power source is developed,which can output two types of current waveforms simultaneously. One is high frequency square current waveform with base current of 0～300 A,peak current of 0～400 A,frequency of 0～80 k Hz,duty ratio of 0～100%,current rate of change of 50 A/μs. The other is variable polarity square wave pulse current waveform with output current amplitude of 0～500 A,frequency of 0～100 Hz,duty ratio of 0～100%,current rate of change of 300 A/ms. The parallel main circuit topology and DSP+ SG3525 A control system mixed with analog and digital IC is adopted. Through software programming,the sync-output of welding current given signal and PWM signal is realized,which can realize high frequency square wave pulse current and variable polarity square wave pulse current output at the same time. The test results show that the high frequency hybrid twin tungsten electrode TIG power source achieves the expected design goal.