The present invention provides a long-term mooring device. A support frame is provided on a dock. The dock is provided with a free guide roller. The free guide roller is wound with a cable. An upper end of the cable is horizontally connected to a spring fixed on a lower side of a cross arm of the support frame, through a free guide roller provided on the lower side of the cross arm of the support frame (corresponding to the free guide roller on the dock). The middle of the cable penetrates through an inertial induction self-locking connection joint fixed on an end of a platform arm. The platform arm is fixed on a platform. The present invention provides an omnidirectional restoring force for the moored platform through the elastic deformation of the springs to control the movement response of the platform within a certain range.