Abstract: The nonlinear coupled equations of fiber Bragg gratings in single-side boundary condition is solved by means of the finite difference method,and based on the result,influence of Kerr-like nonlinearity on the characteristics of the grating is analyzed.The transmission characteristics of the short pulses in the linear and nonlinear operation areas of the uniform and apodized grating are discussed respectively.The results show that at the proper condition,the fiber Bragg grating can be used as optical switch.