In the Magnetic Controlled Reactor’s (MCR’s) control system, it need to sample the current and voltage in the grid.According to the difficulty of measuring high voltage and high current real-time, the design thought of the sampling of high voltage and large current in power system was introduced in detail, and the ac sampling hardware solution based on DSP is proposed. At the same time, the phase compensation circuit and zero crossing detection circuit were designed, and gives the system test results of the circuits. Results show that the proposed scheme solves the sampling problems for voltage and current of Magnetic Controlled Reactor’s control system and the selection problem of thyristor trigger signal datum point.