Sinopliosaurus (meaning "Chinese more lizard") is a dubious genus of pliosauroid plesiosaur.

[1] It lived during the Aptian and Albian stages of the Early Cretaceous[2] (disputed Sinopliosaurus remains have been dated to the Toarcian age and were found in the Ziliujing Formation)[3] of the People's Republic of China - its exact age is unknown.

The type species, Sinopliosaurus weiyuanensis, was named and described in 1944 by Yang Zhongjian.

[3] One species, "S." fusuiensis, was later shown to be based on teeth from a spinosaurid theropod dinosaur which is now known as Siamosaurus.

[4] The holotype, IVPP V140, consists of three vertebrae and a tooth, discovered in a layer of the Lianmugin Formation (Tugulu Group).