The TET gene family has been found a few years ago. Recent studies indicated that TET2 (TET gene family 2) plays an important role in DNA demethylation, the epigenetic regulation and normal hematopoiesis. TET2 mutation has been discovered in a spectrum of myeloid malignancies, including myeloproliferative neoplasms (MPN), myelodysplastic syndrome (MDS) and leukemia, which suggest the role of TET2 as a tumor suppressor. In this review the recent results implicating TET2 in hematological malignancies are summarized, including regulatory functions of TET gene epigenetics, TET2 gene and hematopoietic regulation in bone marrow, TET2 gene and hematological disease(MPN, MDS, AML, CMML, lymphoma) and so on.