It is necessary to study and improve the modulation characteristics of Liquid Crystal Modulator (LCM) because of its wide application. A logarithm driving signal model is proposed to linearize the phase response of LCM between 0 and π. Furthermore, it is found out in the experiments that the degree of phase response linearization of liquid crystal modulator decreases with driving frequency increasing. To overcome this problem, this paper presents mapping the nonlinear phase response to linear one when LCM is driven by a periodic signal constructed of the logarithm model. The experimental results indicate that it is feasible to obtain the linear phase response between 0 and π.