Based on the sublayer division and backward recursion algorithm, a simple and efficient numerical method for calculating the nonlinear reflection spectrum of one-dimensional photonic crystal with one kerr nonlinear defect layer was presented.The nonlinear reflection spectrum in the wavelength range of 1 535 nm to 1 565 nm was obtained by the method.When incident intensity is higher than the threshold, the defect mode moves slowly and appears inclined curved multiple-valued features at certain wavelengths.The influence of incident intensity on jump-up wavelength and jump-down wavelength was analyzed.The influence of parameters of periodic dielectric layer and nonlinear layer on reflection spectrum were investigated systematically.The results showed that the period, high-low refractive index ratio of periodic medium and the thickness of nonlinear defect layer is increased, the defect mode width is narrowed and the threshold of incident intensity, jump-on and jump-down wavelength is decreased.While when the third-order nonlinear coefficient is increased for nonlinear layer, the threshold of incident intensity is decreased and the defect mode width, jump-on and jump-down wavelength threshold is not changed obviously.The multiple-valued feature has an important role in the design of optical switch, optical filter, et al.