Measurement of foot pressure distribution is clinically useful for evaluation of gait pathologies and practically useful for the detection of motion. In order to improve portability of the detection device, this paper come up with a wearable system to detect plantar pressure thus to detect motion. Compared with traditional system, this system utilizes high-precision sensor toenhance portability of the system. In order to improve the compatibility of the system, Inter IC Bus communication protocol and blue-tooth are assembled. Results show that the combination of significant differences for pressure, peak values and correlation between areas could be used to judge common motions. The system is of good practicality and portability.