Polymethyl methacrylate (PMMA) has been proposed as a material for micro-electromechanical systems (MEMS) to initiate the research on environmentally friendly micro-nano machining technology using polymer materials. A polymer MEMS process has been developed using hot embossing and precision machining. MEMS structures less than 2孠were successfully embossed. The PMMA layer that remained after hot embossing was removed by a polishing process to release the movable parts. A PMMA electrostatic comb-drive microactuator was fabricated. Both finger width and gap between fingers were 5孬 and thickness was larger than 70孮 An operated displacement of 11孠at a drive voltage of 100V was obtained. It was 20 times larger than that of an identical silicon device. A torsional micro mirror device driving with vertical comb actuator was fabricated. The size of the mirror was 1ױmm2. The maximum tilt angle of 5.6 was obtained with driving voltage of 100V and frequency up to 100 Hz. A chevron-shaped PMMA thermal actuator with a thickness of about 50孠has been fabricated and tested successfully. The displacement was about 5 times larger than that of a Si counterpart at the same power consumption.