Abstract: Coherent beam combining (CBC) of fiber laser array can improve the total output laser power while maintaining good beam quality, thus improving the laser brightness. CBC of fiber laser array has been a research hotspot in the field of laser technology and has attracted much attention. At present, lots of CBC experiments have been successfully established and verified in the laboratory. However, there is few long distance propagation experiment carried out in real turbulent atmospheric environment. The ability of compensating the phase distortions introduced by the turbulent atmosphere still needs to be tested and verified experimentally. The target-in-the-loop technique is an important and useful method to realize the coherent combining of array beams at the target surface in a real long-distance turbulent atmospheric environment. CBC of fiber lasers based on target-in-the-loop technique becomes a key goal and an important research direction since it has been proposed. Based on the adaptive fiber collimator array and conformal projection system, a target-in-the-loop CBC system of six fiber amplifiers was established, which successfully compensated the phase distortions and realized CBC at the target surface through a kilometer-scale propagation distance with atmospheric turbulence.