Appearance of recent complicated mooring lines demands the development of new method, which is able to be applied for the analysis of dynamic behavior of various types of mooring lines including the deep sea mooring line. In this paper, two-dimensional lumped mass method which was originally developed by Walton and Polachek (1959) have been extended to the three-dimensional method. The present paper also shows the alternative method which is able to include elastic deformation without lengthy procedure of computer simulation. The time histories of dynamic tensions of three-dimensional problem as well as the motions of the line are obtained by the present methods and are compared with the experimental records with excellent agreement.