Abstract: There is a risk of low pressure discharge during the on orbit operation of the internal power system circuit of spacecraft which has high requirements for the working voltage and current. The continuous discharge of internal power system circuit induced by spacecraft surface discharge is studied. The result shows that spacecraft surface discharge will interfere with the circuit of internal power system and aggravate the risk of low pressure discharge. In serious cases, continuous discharge can burn down the internal power system. The result can provide guidance for low pressure discharge protection.