In order to achieve effective transmission of optical signals

the basic principle of different dispersion compensation methods（dispersion compensation fiber and fiber Brag grating）is studied.A single-channel transmission system based on RZ modulation format by Optisystem is designed and two dispersion compensation schemes（pre-compensation

post-compensation）of DCF and FBG is studied.In this paper

the intermediate dispersion compensation method based on FBG is proposed.Simulation results show that the Qvalue of the system is higher than the other two methods when use the FBG intermediate dispersion compensation.The intermediate cascaded FBG module is further proposed as a dispersion compensation device of WDM system.The simulation model in Optisystem is established.Simulation results show that this method can maintain good compensation effect even if the transmission distance is long.