This paper deals with the theoretical and experimental studies of the dynamic tension and displacements of a chain subjected to forced oscillation at its upper end. The chain is anchored in the slack condition on the sea bed and is forced to oscillate vertically with considerably larger amplitude than the cases studied in the previous paper. At first the mechanism of deforming dynamically the mooring line is discussed and then the relation between the dynamic load and deformation of line are formulated approximately. Finally the extended approximate method of calculating the dynamic tension of mooring chain of relatively large amplitude is obtained. The results of calculation by this method coincide fairly well with the experimental results.