Femtosecond laser pulses induce intriguing transient photochemical reactions with semiconductors at the sample surface, due to its ultrashort duration and ultrahigh peak power. Taking advantage of these character-istics, material can be effectively doped. The doping level is likely far beyond the solid solubility limit (so called supersaturated doping), meanwhile quasi-periodic structures with micro/nano- scales are created at the material surface as well. As a result, surface properties are strikingly changed, e.g. ultra-high absorption over a broad range from near ultraviolet to infrared emerges, which breaks the limit of traditional physics and brings novel ap-plications. In this review, we summarize the basic theories and several physical models of femtosecond la-ser-silicon interaction, introduce its applications in relevant areas, and depict future prospects of femtosecond laser hyperdoped and processed silicon.