Based on the characteristics of huge and heavy aircraft blocks merging technology, the application of multi-robot coordination in a merging system for posture alignment is studied. Focusing on the fundamental theories and key technologies of multi-robot coordination system, the system architecture of multiple 3-DOF mobile robots, organization and posture coordinated manipulation method are proposed. By virtue of the blocks merging technology, the blocks' kinematic model is expressed as a body moving with limited linear displacement and rotating with small angular displacement. The coordinates transformation between basic block, merging block and single robot is achieved on the basis of large subassembly merging technology. The trajectory planning method of posture aligning by means of Denavit-Hartenberg method is presented. The proposed method incorporates the behavior of robots and experiences of aircraft blocks mergence into multi-robot coordination. Particular focus on the task complexity, the trajectory of robot joints is also presented after the establishment of relationship among the coordinate system of basis block, merging block and single robot. Measuring data are used to determine the posture of aircraft blocks and guide the process. The object-oriented control algorithm for cooperative multi-robot is derived. The algorithm accommodates various motion types, and controls the blocks motion as well as the result force and endogenous force at the same time. By using the redundancy of multi-robot coordination system and including the constraints of payload, driving force and driving velocity, the trajectory planning strategy of robots combining the endogenous force avoidance with the less energy consumption is achieved. Building a full physical experimental system composed of four 3-DOF mobile robots, a number of key technologies have been developed and integrated, such as trajectory planning, control and coordination strategies.