Abstract: The theory of space mapping is to gain an appropriate surrogate model (aligned coarse model) by constructing aspace relationship between the design variables of coarse and fine model so as to simplify optimization process. This article appliesoriginal space mapping to capacity coupling RF MEMS switch to calculate and optimize, and after iteration a mapping relationshipis constructed and optimized design variables are gained. This mapping relationship enables the optimization work to be done incoarse space instead of fine space, thus time and computer resources are greatly saved. Computing results prove feasibility andefficiency of the technique..