The transmission characteristics of cascaded Bragg grating with defect layers have been studied by simulation.The results show that the resonance peak of the filter increased with increases of the number of cascaded defect layers. The number of cascaded defect layers was the same as the number of resonance peak. And the Bragg grating with seven defect layers have seven resonance peaks. As the number of cycles between defect layers and the length of defect layers increase, the resonant wavelength undergoes center shift and red shift, respectively. Under different defective layer lengths, the maximum resonance wavelength changes rate of the Bragg grating with single, double, and triple defect layers was 0.0477, 0.03021,and 0.03107, respectively. And the number of cycles at the input and output terminals can helps to control the transmittance of the filter. According to the simulation results, the applicable multi-wavelength filter can be obtained by optimally designed the related parameters of defect layers.