To enhance the reliability of array fiber output lasers, the flexibility and high fault tolerance of the k/n (G) voting model are exploited, and the redundant design of the fiber array is carried out by using a cold reserve unit, so as to achieve the service life enhancement under the premise of controllable laser output power. The k/n∶M (G) cold standby voting system consists of n working units and M cold standby units, and the system works normally when at least k units work properly. In this paper, a 3/5∶2(G) cold standby voting system equivalent model is established by combining a 5-module controllable array fiber laser, the reliability and average lifespan of the fiber laser under different redundancy strategies are solved, and then the voting system is optimized according to the best strategy. Finally, the Monte Carlo simulation test is used to prove the correctness and feasibility of the method.