Picosecond laser has picosecond (10-12 s) pulse width, which is the same as the electro-optical relaxation time (10-6-10-12 s) or even shorter. When picosecond laser interacts with materials, there is no enough time for electron to transfer the energy to crystal lattice. Therefore, there's little heating effect during fabrication, which is called cold ablation. This technology is widely used for precision machining in astronautics, national defense, materials, medical science, biological science and so on. The technique of micro-nano fabrication by picosecond lasers is introduced and the precision drilling on high hardness metal, the hard and brittle materials cutting and the selective surface removal with picosecond lasers are summarized. The challenges and future trends of micro-nano fabrication by picosecond lasers are pointed out.