Abstract: Myeloproliferative neoplasms (MPNs) result from clonal expansion of haematopoietic stem cells and are characterized by abnormal proliferation of myeloid lineage cells in the bone marrow. Sustained activation of JAK-STAT signaling pathway due to JAK2 phosphorylation is an important cause of MPNs, and mutation of JAK2 kinase can keep it in a state of continuous phosphorylation. The most typical mutation in JAK2 is a site mutation of V617F in the pseudokinase domain. The JAK2V617F-activating mutation is highly prevalent in MPNs, with frequencies estimated at approximately 95% in polycythaemia vera (PV) and 50% in primary myelofibrosis (PMF) and essential thrombocytosis (ET) patients. It is now clear that JAK2 is an important target for treatment of MPNs. Inhibiting aberrant activation of the JAK2-STAT signaling pathway has become a popular trend in research for effective treatment of MPNs. This review summarizes the research progress in developing JAK2 inhibitors for treatment of MPNs in recent years, including the new discoveries of the biological functions of JAK2, the relationship between JAK2 and MPN, and the status of development of JAK2 small molecule inhibitors.