With an extraodinary complex structure structure, the Fourth Nanjing Yangtze River Bridge, a three-span continuous suspension bridge, is scarce in the world. This paper is to elaborate the structure characteristic by comparing and analysising the following aspects： the span-rise ratio, support at cable tower, limitation of longitudinal displacement and vertical displacement, as well as to propose a propor structure system, three-span continuous elastic supporting suspension bridge structure system, according to the pactical issue of the Fourth Nanjing Yangtze River Bridge, which is of innovative significance.