The design of micro structure is according to the process specification of National Chip Implementation Center. A CMOS-MEMS micro structure is applied to sensing the micron scale crack of bridge pier based on TSMC 0.35μm 2P4M COMS-MEMS common process. The components will be installed in where bridge pier may have cracks, when the bridge piers generate micron scale cracks due to external shocks. The leverage principle of the micro structure results in the reverse displacement. And that brings the changes in the overlapping area between the upper and lower electrodes of the micro structure and results in a change of capacitance. The width of the cracks is measured by measuring the capacitance. The electrical signals are sent out to achieve automatic detection and warning by using the amplifier and wireless transmission circuits. In addition, the micro structure with micro springs design prevents from being broken due to the excess external force. Spring structure can reduce the stress within the component. When the thickness of spring structure is 0.64 μm, the width is 2μm and the pitch number of spring is 4 with the spring constant 0.1765, and those make an effective decrease on the stress of the micro structure. The sensing micro structure of the micron scale crack can significantly enhance the performance of sensing cracks of the bridge pier.