This paper analyzes the analog acquisition system of the current 10 kV protective device, and presents a method of the lowcost plesiochronous sampling system in Distribution Terminal Unit. This system uses the V sampling interpolation method, and realizes the plesiochronous sampling of analog data bye using the flexible configuration and high-speed conversion between input channels of the AD7616 chip. This design, based ZYNQ platform, uses internal AXI bus to realize the high speed transmission. This design greatly improves the reliability and real-time of AD data and ensures the security and stability of the power grid.