沧龙亚科（Mosasaurinae）是有鳞目沧龙科的一科，生存于白垩纪晚期。

在1967年，戴尔·罗素（Dale Russell）将沧龙亚科定义为具有以下特征：前上颌骨前方的喙小，或是没有、齿骨与上颌骨具有14颗以上的牙齿。第五、六、七对脑神经穿越耳后的两个孔、枕骨底部或基蝶骨没有基底动脉的血管沟、方骨的上镫骨突末端扩张、至少有31节荐前椎，多为42到45节、荐前的脊椎总长，长于荐后的脊椎总长、后端尾椎的神经棘长，形成尾鳍、四肢关节的表面平顺、距骨与腕骨高度骨化。

在1997年，G. L. Jr. Bell出新的沧龙超科的系统发生学研究，仍将沧龙亚科保持为一个演化支的地位，但将倾齿龙族改归类于沧龙亚科，并新建圆齿龙族。

Mosasaurinae is a subgroup of mosasaurid marine lizards.

Russell (1967, pp. 123–124) defined the Mosasurinae as differing from all other mosasaurs as follows: "Small rostrum present or absent anterior to premaxillary teeth. Fourteen or more teeth present in dentary and maxilla. Cranial nerves X, XI, and XII leave lateral wall of opisthotic through two foramina. No canal or groove in floor of basioccipital or basisphenoid for basilar artery. Suprastapedial process of quadrate distally expanded. Dorsal edge of surangular thin lamina of bone rising anteriorly to posterior surface of coronoid...At least 31, usually 42–45 presacral vertebrae present. Length of presacral series exceeds that of postsacral, neural spines of posterior caudal vertebrae elongated to form distinct fin. Appendicular elements with smoothly finished articular surfaces, tarsus and carpus well ossified." In his 1997 revision of the phylogeny of the Mosasauroidea, Bell (pp. 293–332) retained the Mosasaurinae as a clade, though he reassigned Russell's tribe Prognathodontini to the Mosasaurinae and recognized a new tribe of mosasaurines, the Globidensini.