Real -time monitoring of foundation pits is an important part of the engineering construction. This paper proposes a method of deformation monitoring of foundation pit based on MEMS technology. The algorithm based on time-domain integration is adopted, and a fixed distance test is designed to verify the feasibility of the algorithm. Through the indoor model test of foundation pit monitoring, MEMS sensors are embedded to collect the acceleration, rotation angle and the other signals of soil movement, and then the acceleration signal is integrated to obtain displacement by algorithm calculation. Finally, the deformation characteristics of soil in the process of foundation pit are analyzed by using soil displacement and rotation angle to investigate the effectiveness of applying MEMS technology to foundation pit monitoring. The test results show that the MEMS sensor could accurately collect the acceleration, rotation angle and other signals of soil movement in model box. The monitoring method proposed in this paper lay a theoretical foundation and experimental verification for the application of MEMS technology in foundation pit monitoring.