Abstract: Hsisosuchus chungkingensis was described by Young and Chow (1953) on the basis of a cranium and some caudal osteoderms of an old individual from the Late Jurassic Shangshaximiao Formation, near Chongqing (Chungking) city, Sichuan proVince, China. A new family, the Hsisosuchidae, was then erected for this species on the basis of a number of peculiar features, such as the closure of the suborbital fenestra, the closure of the external mandibular fenestra and the presence of a pronounced transverse ridge of the pterygoid across the palate. H. chungkingensis is as yet a poorly known taxa, because certain aspects of the cranial anatomy are obscured by extensive fusions among elements and the lack of its postcranium. A new specimen of Hsisosuchus chungkingensis, including the cranium and most of the postcranium, was collected by one of us (X.-M. Li) in early 1960s from the Jurassic sandstone of the Sangqiao area, Yongchuan county, about 60 km southwest of Chongqing. This specimen probably represents a young adult or a subadult, as indicated by its small size (less than 2/3 length of the type, based on the skull proportion) and open sutures between palatal elements. In the present paper we will redescribe H. chungkingensis in detail based on both the type and newly discovered specimens in order to clarify anatomical uncertainties, establish a suite of diagnostic features and discuss age variations of certain aspects between the type and new specimens. The close affinity of Hsisoswchus chungkingensis to the Sebecidae suggested by Young and Chow on the basis of the tooth morphology and later supported by others such as Langston (1956), Berg (1966), Kuhn (1968) has been challenged by Buffetaut (1979, 1982). A cladistic analysis on the phylogenetic relationship of H. chungkingensis within the Crocodyliformes (Clark, 1986) will be discussed in a following paper. The new material used in this study is housed in Chongqing Natural Museum (CNM V1090), Sichuan, China.