The kinematical principle and mechanical characteristic of the cell membrane stress modulator are analyzed, which is a key equipment of the external cell bringing up experimental system. A designing project of the experimental system is put forward based on position measurement and controlling modulating region. It validates that the design can improve the mechanical characteristic of the device. At the same time, the device can work smoothly, the life time of its correlative parts can be increased, and the power waste of the system can be reduced.