A digital servo control system with high frequency response and data record is proposed by using Beckhoff Company Industry Computer, AD module and DA module as main hardware, TwinCAT(The Windows Control and Automation Technology) as real-time operation system. The PID control program is based on TwinCAT Programmable Logic Controller(PLC) and the control interface and data record program are based on C# language. The designed servo control system works steadily with 50 μs data update period, 150 μs delay between output and input and can record data without data losing. It has sweep-frequency signals source with square, triangle, sine wave optional and can be used in system frequency characteristic test. Experimental results show that the designed control system based on TwinCAT has high frequency response and high stability which can be used in servo control systems and frequency characteristic test.