a fault initial phase controlled system for physical simulation experiment of single-phase grounding fault is designed. The effect of fault initial phase on characteristics of transient signals is analyzed. Design principles and operating logic of fault initial phase controlled system is given. Hardware components and software control process is mainly discussed. Hardware components include zero-crossing detection circuit, MCU and SCR drive circuit. Software control process describes working program flow of CPU. Taking the fault initial phase controlled system connected to a static simulation system for active distribution network and doing the single-phase grounding fault experiment, the results show that fault initial phase can be precisely controlled by the system.