The formation conditions and the energy variation of surface waves at the interface between a metal and a photorefractive crystal are investigated by using the particle oscillator model and numerical techniques. Our analysis indicates that the positive and negative values of the propagation constant affect the type of surface waves and the energy distribution: formation surface waves are nonlocal surface waves for negative values of the propagation constant and are oscillating surface waves and localized surface waves for positive values of the propagation constant, and the energy of localized surface waves in photorefractive medium increases monotonically with the propagation constant value increasing. In a given physical system, one can control the different orders and the waveforms of localized surface waves by regulating the variable parameter determining the strength of nonlinear effects.