A test principle and the design method for projectile's mechanical parameter measuring system were introduced. The core of the hardware circuit is the single chip. The hardware circuit realizes the functions such as signal measurement, motor control and communication between the PC and the single chip. The software of the host is programmed by Lab Windows/CVI, which realizes command transmission, data receipt, management and display. The system overcomes the shortage of traditional measurement method, realizes test automation. The project is reasonable and feasible.