Based on the coupled-mode theory of fiber grating and codes theory, the design of an optical code division multiple access (OCDMA) encoder/decoder with stepped chirped fiber Bragg grating (SCFBG) has been proposed. The length of each uniform subgrating, the realization of encoding and decoding are provided. Numerical result is also presented and discussed. Based on the coupled-mode theory of fiber grating and codes theory, the design of an optical code division multiple access (OCDMA) encoder / decoder with stepped chirped fiber Bragg grating (SCFBG) has been proposed. The length of each uniform subgrating, the realization of encoding and decoding are provided. Numerical result is also presented and discussed.