The extremely small size of the micro-electromechanical systems (MEMS) makes them widely suitable for some special applications. The simplicity of the piezoelectric micro-generators is attractive for MEMS applications, especially for remote systems. In this paper, a general concept of the piezoelectric energy conversion is first given. A simple design modeling and analysis of the ‘31’ transverse mode type piezoelectric micro-generator is presented. The output power is taken as the indicated parameters for the generator. The energy conversion efficiency of the generator, which is dependent on the operation frequency, is expressed in the frequency domain. A case study of laminated type micro-generators using PZT-PIC 255 for MEMS applications is given and the use of single crystal PZN-8%PT is also studied for comparison. Some design guidelines are presented based on the simulation results.