Optical en/decoder,based on fiber Bragg grating (FBG) arrays plays as a key role in a 2-demension hybrid time-spreading and wavelength hopping optical code division multiple-access (OCDMA) system. Suppressing the interference between the wavelengths of the encoder is investigated,and the performance of the encoder with the Gaussian apodized FBG is improved. The theory and the model of the encoder/decoder in 2-demension hybrid time-spreading and wavelength hopping OCDMA system are given,and the performance of the FBG encoder/decoder in time domain is analyzed. The mathematic models of the wavelength mismatch in FBG are presented. The auto-correlation peak of the decoding signal is used to quantitatively evaluate the encoder/decoder performance,analyse some kinds of encoder/decoder wavelength mismatch. According to the analysis and simulation,it can be pointed out that large number of son-arrays will improves the system′s capacity for anti-interference,but the biterror rate (BER) performance and data speed will degrade.