The theoretical model of the interaction between femtosecond lasers and crystal materials is established, in which the effects of electron excitation, carrier absorption and other ionizing process are coupled into the classical double-temperature model. The variations of the electron and lattice temperature with the pulse duration and fluence of femtosecond lasers in MgO∶LiNbO3 crystals with different doping concentration are numerically simulated by the finite-difference method. Furthermore, the variation of damage threshold with the femtosecond pulse width and influence in different doping concentration MgO∶LiNbO3 crystals, as well as the influence of doping concentration on damage threshold are analyzed quantitatively. Results show that, in appropriate doping range, with relatively higher MgO-doped concentration, the carrier mobility of MgO∶LiNbO3 crystals increases, and the damage threshold of the crystals becomes higher. Consequently, the resist damage capability of LiNbO3 crystal may be raised by appropriate MgO doping in practical applications.