Abstract: To make the design and fabrication of planar W-form micro-springs based on MEMS technology convenient,expressions used to calculate the micro-spring made of different materials constant by its structural parameters are derived by energy method,and subsequently verified correct with tensile test and ANSYS finite element method using nickel planar W-form micro-springs.The stiffness response of the micro-spring to its structural parameters was also analyzed by the formula precedingly derived and the simulation results.Therefore the reliability and the optimization design of MEMS can be improved.