The generation of F+2-centers in LiF crystals is studied. Experiments show that in order to acquire a better understanding of the physical processes involved, two parameters, dosage-rate r and irradiation-time t rather than a single one, dosage R should be used to specify the irradiation condition. The density in the order of 1016 F+2-centers per cubic centimeter is obtained in our experiments. The density of F+2-centers depends on both the radiation source and the quality of the crystals. An expression derived from the experiments for maximum density is given by Nmax = krT. In addition) judging from the residual fluorescence of F^-oen fcers in LiF crystals， it seems reasonable io assume that two states of F2-centers exist in LiF crystals. The life-iime of F^-centers is also measured.