Assiminea sinensis is a species of minute, salt-tolerant snail with an operculum, an aquatic gastropod molluscs, or micromolluscs, in the family Assimineidae.
The length of this species attains 5 mm, its diameter 3 mm.
(Original description in Latin) The shell is imperforate, ovate-conical, and rather solid. It is shining, nearly smooth and chestnut-brown. It is marked by a slightly faint impressed line below the suture. The spire is elongated and conical, with a somewhat acute apex. It has 7ý rather flattened whorls. The body whorl is compressed, scarcely convex, and furnished with no keel. The aperture is small and nearly vertical. The margins are joined by a somewhat obsolete callus. The outer lip is thin. The inner lip is arched, thickened, and dark chestnut-brown. It is subangulate below.
This species occurs in Hong Kong in brackish waters.