Abstract: In order to analyze the effect of the incident wavelength drift from the design wavelength of phase Fresnel lens on the focusing property of phase Fresnel lens, the dependent curves of focal power-wavelength and diffractive efficiencywavelength for the phase Fresnel lens were obtained by adopting the finitedifference time-domain method (FDTD) as a rigorous vector analysis tool. The simulation results show that the focal power of a Fresnel lens increases with the wavelength, which is similar to the result of scale theory, the diffractive efficiency declines with the drifting of the incident wavelength, and it is lower than the analysis result of scale theory.