The invention discloses a marine floating type drilling riser flexible hander which mainly comprises a chuck-universal joint assembly, a motion compensation device, a guide mechanism and a hydraulic power unit. The chuck-universal joint assembly is combined by adopting an embedded structure, suspension and up-down of a water string can be achieved, and it is ensured that the chuck swings by a certain angle along with a riser; a distance-increasing type motion compensation hydraulic cylinder is adopted on the motion compensation device to drive the chuck-universal joint assembly to do compensation motion. The guide mechanism ensures that the chuck-universal joint assembly does rectilinear motion along a guide rail through sliding fit of a sliding block installed on the chuck-universal joint assembly and the guide rail, and the radial load of the riser is borne. The hydraulic power unit provides power and control for the whole device. On the basis of achieving the conventional suspension and up-down operation function, the system structure height is lowered, the riser suspension operation step is simplified, suspension time is shortened, the variation amplitude of the load in the riser is lowered, and the suspension performance and reliability of the riser are improved.