Microfabrication is a kind of critical technology for the development of Micro Electro-Mechanical Systems (MEMS). The frequently-used microfabrication technologies are electric discharge machining, photoetching, LIGA and laser fabrication, et al. Micro structures may be fabricated by these technologies. The polymerization principle of two-photon of femtosecond laser is different from that of single-photon. Photoinitiator of photosensing material absorbs two photons simultaneously to accomplish energy level transition and to induce the material to occur photochemical reaction. For the material absorbing two photons, the energy of each photon is equivalent to half of the energy that needed by the material transiting from ground state to excited state. It is also equal to half of the energy needed by the material occurring single-photon absorption. Therefore, the photonic frequency of two-photon excitation light source is half of the single-photon light source. According to two-photon fabrication principle, machining system of two-photon of femtosecond laser is set up. Which includes light path transmission equipment, three dimensional micro displacement scanning stage and control software, et al. Involute micro gear is fabricated by two-photon of femtosecond laser generated by the system.