The Banghu SubSag is the depositional and subsidence center of the Qianjiang Formation in Qianjiang Sag. Origins of sandbodies along its two sides and their distribution have been a controversial topic. Their origins have been distinguished by core observation， hydrodynamic analyses and clastic zircon dating analysis. Further more， the relationship between palaeogeomorphology and sandbody distribution was identified. The research indicates that during the deposition of the Member 3 of the Qianjiang Formation,  two provenances—Jingmen and Hanshui were developed in the north，the BanghuWangchang SubSag was developed in the central area，a “Y” shaped low uplift and a slope was present in the west，a slope belt was developed in the east and expansive gypsumbearing mudstones of shoreshallow lacustrine origin were deposited in the south slope belt. New research results show that during the deposition of the Member 3 of Qianjiang Formation，the sandbodies along the south side of the Banghu SubSag were neither deposits of salt density fluid flowing through the Banghu SubSag， nor transported by traction， but transported and deposited along the ditchtrough or west slope by traction.