With the continuous development of medicine, optics, chemistry, communication and other fields, various micro total analysis system, lab-on-a-chip, micro electro mechanical systems and high-precision micro-nano devices began to appear and are gradually used. Most of these systems or structures are realized by preparing three-dimensional micro-nano connected structures in transparent materials by femtosecond laser. Therefore, the main technologies of femtosecond laser preparation of three-dimensional micro-nano structures are introduced, the main applications of micro-nano connectedstructures are summarized, the existing problems of current femtosecond laser preparation of three-dimensional micro-nano connected structures are put forward, and the technology is prospected.