The invention provides a mooring system rigidity automatically measuring and testing device of an ocean structure and belongs to the ocean engineering technical field. The device comprises a model movement control component, a model connecting component and a turntable, wherein, the model movement control component comprises two convex steel plates, two straight circular tubes, two parallel angleirons, five sliding blocks, a servomotor and a guide screw, the two sides of the lower ends between the two convex steel plates are welded with the two parallel straight circular tubes, the two sidesof the upper ends between the two convex steel plates are welded with two parallel angle irons, the guide screw is arranged between the two convex steel plates, the servomotor is positioned outside the convex steel plate on the right side and is welded with the extension parts of the two parallel angle irons, the servomotor is connected with the guide screw by a pin, the guide screw is sleeved bya sliding block, the lower end of the sliding block is welded on a square steel plate, the four corners of the square steel plate are welded with the other four sliding blocks with the same forms, thefour sliding blocks are respectively sleeved on the two straight circular tubes. The invention overcomes the difficulty of the manual operation, can automatically measure the rigidity of the mooringsystem in the water and corresponds with the real working environment.