We report the space-selective formation of colour centres and refractive index change in LiF crystals at room temperature by an 800nm Ti:sapphire femtosecond laser irradiation. Optical absorption and photoluminescence spectra have been measured for the crystal before and after the laser irradiation. The absorption spectra indicate F and F+3 colour centres are induced in LiF after the laser irradiation. When the temperature of heat treatment reaches 300 ℃, the absorption peak disappears, indicating that the induced colour centres are bleached. The induced refractive index change is also evaluated. A mechanism for the formation of colour centres and refractive index change is proposed.