In view of the requirement of the small size strapdown inertial navigation system in the special environments such as oil, coal mine and so on, a strapdown inertial navigation system based on FPGA single chip control and MEMS IMU is designed in this paper. The system uses ADI MEMS IMU as the inertial component, cyclone III series FPGA as the control chip, and the System on Programmable Chip (SOPC) operating mode to construct a strapdown inertial navigation system with the size of 4 cm×11 cm. The system realizes the functions of data acquisition, error compensation, navigation solution and communication with the host computer. The experimental results show that the system can meet the requirements of small size measurement environments such as drilling etc. The attitude error is less than 2° during the attitude changing process with steady operation.