This paper presents an analysis on efficiency improvement of class-E power amplifiers (PAs) with Microelectrome chanical systems (MEMS) inductors. The efficiency can be improved and has been demonstrated by using MEMS inductors. The proposed MEMS technology is validated by a prototype MEMS inductor. Also, the simulation result of MEMS inductors by HFSS have good match with the measured result. The stacked-metal layer inductors implemented in MEMS process are developed for increasing the quality factor. The simulation result of a CMOS class-E PA with MEMS inductors shows that the increased quality factor of inductors by 2 can improve the drain efficiency by 6%. Therefore, we present a design methodology that can improve the efficiency of PAs by optimizing the quality factor of fully integrated inductors.