An optimization model of peak valley price interval of electric vehicles based on comprehensive index is presented considering the problem of guiding the orderly charging and discharging of electric vehicles to reduce the peak valley difference.A random charging and discharging model based on travel habits and an orderly charging and discharging model based on peak valley price time interval are respectively established, based on which, an optimization model is proposed whose optimization objective considers both peak valley difference improvement and users’satisfaction of power consumption mode. An optimal peak valley price time interval scheme is obtained using genetic algorithm. An example shows that the scheme obtained can guarantee users’satisfaction while reducing the peak valley difference.