In order to solve the power quantity problem of negative sequence current and harmonic current in high-speed railway, railway static power conditioner (RPC) was adopted. RPC contains two inverters which are connected with each other by sharing a DC capacitor, the negative sequence current and harmonic current can be restrained together by controlling the power of the two inverters. The structure and compensation principle of RPC was introduced, and the negative sequence current and harmonic current compensating reference detecting method for three-phase Vv transformer was presented. To maintain the DC voltage and compensate negative sequence and harmonic current,