The motion equation and mechanical characteristics of moored floating body are important research directions of offshore floating structures. Aiming at the difference of response law and mechanical change of floating body in different degrees of freedom, the motion and mechanical balance equations of multiple degree of freedom mooring floating body are established based on decoupling analysis method. Combined with the mechanical simulation model, the time-domain motion variation law and the corresponding relationship of the external force of the mooring floating body in the six degrees of freedom of surge, sway, heave, roll, pitch and yaw are analyzed in detail. The paper focuses on the influence of mooring force on the motion and stability of the floating body, and provides a theoretical reference for the dynamic research of offshore mooring floating structure. In addition, based on the six degree of freedom equations and simulation results, combined with the motion response law of traditional tension type and catenary type mooring schemes, two-points and four-points mooring optimization schemes are proposed. Through simulation and comparison, the superiority of two-points and four-points mooring schemes in motion response and mechanical performance of multiple degree of freedom floating body is verified, which provides important theoretical basis and support for the research of time-domain variation law of mooring system and marine safety control.