The development of multi-channel optical fiber communication system not only shares the pressure of concurrent user communication requests ,but also makes the problem of signal deviation more and more serious ,lead- ing to the decline of communication reliability and the aggravation of communication delay. Aiming at the above prob- lems ,a signal bias control method for multi-channel optical fiber communication system is studied. Use the collector to obtain the channel signal and pilot channel signal of the communication system in the same time period and imple- ment filtering processing ,calculate the similarity between the two signals ,and detect whether there is signal deviation. The phase difference between the two signals is calculated by using the zero point comparison method. Through the in- troduction of correction scale factor and the adjustment of particle swarm optimization algorithm ,the PID signal devia- tion controller is optimized ,and the signal deviation control quantity of multi-channel optical fiber communication sys- tem is obtained by taking the phase difference as the input. The results show that the similarity between the three chan-nel communication signals and pilot channel signals after control is greater than that before control ,and both are grea- ter than 0. 95 ,which shows that the control method studied is effective and suppresses the signal deviation phenome- non.