As the typical series from of multiterminal DC(MTDC) transmission technology, cascade multiterminal UHVDC (CMTUHVDC) power transmission technology has good prospects for development. Base on the typical connection mode and configuration consideration of CMTUHVDC and according to the life cycle theory, the economic influence factors of CMTUHVDC and Twoterminal UHVDC selection are quantitatively analyzed, providing reference for CMTUHVDC selection.