Tumor protein D52-like 2, known as hD54 in previous studies (TPD52L2), is a member of TPD52 family which has been implicated in multiple human cancers. In recent reports, TPD52 proteins were indicated to be associated with several malignancies, but very little is known about the function of TPD52L2 in liver cancers. In our present study, in order to explore the role of TPD52L2 in liver cancer, TPD52L2 was knocked down in SMMC-7721 liver cancer cell line by lentivirus mediated RNA interference. The results demonstrated that depletion of TPD52L2 could remarkably inhibit proliferation and colony forming ability of cancer cell SMMC-7721. Furthermore, cell cycle in TPD52L2 depleted cells was verified to be arrested in G0/G1 phase as determined by FACS assay, in consistence with the observation of cell proliferation inhibition. These results unraveled that TPD52L2 played an important role in tumorigenesis pathways of liver cancer and might serve as a promising target in human liver cancer diagnosis and therapy.