Based on the theory of impact dynamics, the motion equations for a mooting line-floating body system before and af-ter impact loading are established with consideration of the viscoelastic property of mooring lines. The factors that influ-ence the taut-slack conditions of a mooring system are analyzed through classifying the taut-slack regions, which are de-fined by non-dimensional ratios of displacement, frequency, and damping of the system. The mooting system of Jip spar platform is analyzed, and the snap tension characteristics of mooring lines are given. The factors that influence the maxi-mum tension in mooring lines, including the mass of the floating body, length of mooring lines, frequency and amplitude of external excitation, and pretension in mooring lines, are also analyzed through computing the dynamic response of sys-tem and parametric study. It is shown that the maximum tension increases with the increasing mass of the floating body, external excitation and pretension. Also, it is found that the influence of the non-dimensional ratio of damping increases with the increase of the pretension in mooring lines.