Aiming at the disadvantages of traditional inverter precharge circuit such as optocoupler isolation and additional circuit participation, complex software algorithm and inconvenient debugging, a precharge circuit with constant current adaptive function is designed. The circuit adopts a structure similar to buck circuit. It adaptively maintains closed-loop stability, provides relatively stable power supply for thyristor triggering, and can realize alternate opening of each phase thyristor without relying on software participation. At the same time, there is no need to pay attention to the optocoupler isolation and the timing issue of switching power supply priority. The PSIM simulation results are consistent with the test results of the physical platform. The test waveform shows that the circuit scheme is feasible and easy to debug, and it has certain reference value.