Firstly, this paper analyzes functions and composition of the aircraft structural parts digital assembly system, and propose the four key technologies of digital assembly system. This article studies the assembly of the outer and the central wing from the measurement field construction, initial position calibration of the assembly system, assembly path planning, and measurement error compensation four aspects, and achieves the Posture Alignment and error measurement and control of the assembly system, completes the precision assembly of the outer and the central wing.