Abstract:  A new sauropod dinosaur, Huangshanlong anhuiensis gen. et sp. nov. is described based on specimens including right humerus, radius, and ulna from the Middle Jurassic Hongqin Formation of Shexian, Huangshan, Anhui Province. Comparative studies show thatHuangshanlong can be assigned to Mamenchisauridae. Members of Mamenchisauridae, including Huangshanlong, have 25° outward torsion of the distal end of the humerus, well-developed two accessory processes on the cranial edge of the distal end of the humerus, and well-developed two cranial processes on the proximal end of the ulna which forms an angle of 90° or slightly less. Compared to other members of Mamenchisauridae, Huangshanlong possesses a unique combination of features, such as transverse length of the proximal end of the humerus is 36% of the total length of the humerus, accessory processes are located near the middle of the cranial edge of the distal end of the humerus, length of the radius is 58% of that of the humerus, length of the ulna is two thirds of that of the humerus, craniomedial process on the proximal end of the ulna is longer than the craniolateral one, and ridges develop on the cranial, caudomedial, and caudolateral faces of the distal portion of the ulna. Huangshanlong represents the first Jurassic as well as the second dinosaur species in Anhui Province.