Coherent combining of fiber lasers is an effective approach to pass through the power limitation of single channel fiber laser and achieve high output power, and is also an important foundation for the traditional high power laser system developing towards laser phased array of high power fiber laser system. The system configuration of high power fiber laser coherent combining is introduced, and the main study object and the key technique are pointed out. The research status and development tendency of fiber laser coherent combining are presented. The main technique challenges for fiber laser coherent combining are analyzed.