In view of the deficiency existing in current dynamic test method and demand for dynamic testing of missile servo mechanism, a dynamic test system was designed based on chirp signal test. The test system consists of data acquisition and signal generation module, servo amplifier circuit, signal conditioning circuit, display, mouse/keyboard and printer, etc. IPC-610L industrial computer and PCI-1706U multi-function data acquisition card were utilized to construct the test system hardware, and computer interface was realized by c # programming. System function includes self-check, excitation signal generation, data acquisition, data processing and test data management. In the process of testing, dynamic test system is sustainable producing ultra-low frequency signal, and synchronous sampling input excitation and output response. Chirp signal is taken as excitation signal to incentive system mode fully and FFT transform is applied to calculate dynamic performance. Test results show that the system can rapidly and accurately obtain system frequency characteristics and shorten test time.