By using FPGA high speed parallel processing features, design the AC servo high-precision feed-back system based on FPGA. The system total design concept is given, design and realize the high-speed high-precision data acquisition system for position loop, speed loop and current loop. The designed system is tested on a 1kW permanent magnet synchronous motor (PMSM) AC servo platform. The test result shows that the designed system can overcoming the defect of single DSP that can not perform the functions of algorithm control and acquisition of feed-back information simultaneously, improves real-time performance and accuracy of data acquisition of feed-back system, hence enhances the bandwidth and overall performance of the servo control system.