Aiming at the requirements of the quality, control speed and control accuracy of the synthetic beam in the linear array fiber laser coherent synthesis system, the design of the linear array fiber laser coherent synthesis controller is completed. The controller uses DSP2812 and CPLD as the core processor, receives the voltage signal of the photodetector through AD976A analog-to-digital converter, and outputs analog voltage from AD8544 digital to analog converter to control the piezoelectric ceramic phase controller, and then controls the phase change of the light. In order to realize the communication between the controller and the target image detection board and the upper computer, two serial communication interfaces are designed, and related test procedures have been written. Finally, the coherent synthesis, scanning and tracking experiments of four 1 064 nm lasers are completed in the linear array fiber laser coherent synthesis system. The experimental results show that the controller is equipped with SPGD algorithm, and can realize fiber laser phase locked with the cooperation of photodetectors. After phase locked, the energy change of the main lobe is better than ± 5%, and the scanned range of the main lobe is ± λ. The scanned frequency is about 25 Hz. At the same time, the target tracked experiment is completed in combination with the target image detection board to realize the target tracked of laser coherent synthetic stripes.