The invention provides a suspended type mechanical system for aeroengine main unit body centering assembly. The suspended type mechanical system is composed of an upper fixing frame (1), a posture adjusting platform horizontal feeding mechanism (2), a tension adjusting device horizontal feeding mechanism (3), a posture adjusting platform lifting mechanism (4), a posture adjusting platform (5), a high-accuracy horizontal feeding mechanism (6), a force sensor (7), an adapting tool (8), a horizontal lifting appliance (9), a to-be-assembled body (10) and a tension adjusting device (11). Through the mechanical system, flexible adjustment of the positions of an assembling and posture adjusting mechanism in the horizontal and vertical directions can be achieved; and meanwhile through the postureadjusting mechanism, six-degree-of-freedom position and posture adjustment can be achieved, the posture adjusting task in the aeroengine main unit body centering assembly process is met accordingly, and through the force sensor, force in the assembly process can be measured in real time. The system is high in modulation extent, flexible in use, efficient, convenient and rapid.