Abstract: The present invention relates to a linkage test apparatus for deepwater drilling riser and hang-off system. The linkage test apparatus includes a motion excitation system, a hang-off system and a riser system. The motion excitation system includes a six-degree-of-freedom excitation platform and sensors. The hang-off system includes a hydraulic cylinder actuating mechanism and a hydraulic system. The hydraulic cylinder in the hydraulic cylinder actuating mechanism is composed of an inner cylinder and an outer cylinder and it is fixed on the six-degree-of-freedom excitation platform by a spider. The inner cylinder of the hydraulic cylinder is hollow. A hang-off joint passes through the center of the inner cylinder, and a bottom of the hang-off joint is connected to the riser system via a rotating flange. The riser system is successively connected by multiple riser test joints, and the bottom is suspended with a lower marine riser package model.