The acquisition system based on hardware circuit control has more advantages in stability and rapidity than the acquisition system controlled by software. Using heterogeneous platform to complete the acquisition of various parameters of power grid based on hardware circuit is a basic work of smart grid. Therefore, a set of multi-channel data acquisition system based on heterogeneous platform Zynq-7020 is designed to meet the measurement and monitoring requirements of insulation oil temperature and water content in transformer. Firstly, the paper expounds the design idea. Then, taking the heterogeneous platform integrating ARM and FPGA as the core, the system circuit is designed. Furthermore, the design of data acquisition, processing and transmission is completed based on Verilog and C language. Finally, the experimental data of the system are given. The experimental results show that the system has the characteristics of strong expansibility, high precision and strong stability.