The target-in-the-loop (TIL) fiber laser array adaptive phase-locking technique is studied theoretically and experimentally. The system configurations of TIL adaptive phase-locked fiber laser array and the fundamental theory for single-dithering algorithm are introduced. The performance of TIL adaptive phase-locked fiber laser array under high-power laser is studied. Two high-power fiber amplifiers are set up and the adaptive phase-locking of two 10-W-level fiber amplifiers is accomplished by implementing single-dithering algorithm on a signal processor. The experimental results demonstrate that the optical phase noise for each beam channel can be effectively controlled by the TIL adaptive optics system and the fringe contrast is increased to 73%.