Abstract: Based on the relationship of the dispersion and absorption (gain) coefficient in laser classical theory, the dispersive characteristics of Ti:sapphire crystal has been discussed in this paper.According to the spectroscopy of Ti:sapphire,the abnormal dispersive curve(in absorption region) and normal dispersive curve(in normal region) are obtained. These results show that the refractive index variation of Ti:sapphire rised from the absorption and gain can be negligible and can be treated as normal dispersion.