To investigate the relationship between JAK2 gene mutation and clinical indicators in patients with myeloproliferative neoplasms (MPN). 122 MPN patients in the Department of Hematology, Xiyuan Hospital, China Academy of Chinese Medical Sciences from September 2017 to January 2020 were retrospectively analyzed. The relationship between JAK2 gene mutation and sex, age, peripheral blood cell count, splenomegaly, and thrombosis and bleeding events were analyzed. In 122 patients with MPN, the patients with polycythemia vera (PV) accounted for 36 (29.5%), the patients with essential thrombocythemia (ET) accounted for 56 (45.9%), the patients with myelofibrosis (MF) accounted for 30 (24.6%). The JAK2 gene mutation rate in MPN patients was 64.6% (79/122), and the JAK2 gene mutation rate in PV, ET and MF groups were 77.7% (28/36), 60.7% (34/56) and 56.7% (17/30), the JAK2 gene mutation rate of the patients in PV group was statistically significant as compared with those in the ET group (P<0.05). The hemoglobin (Hb) count of the patients in JAK2 gene mutation group was higher than those in wild-type group [(150.0±39.6)g/L vs (129.4±38.9)g/L, P<0.05]; the white blood cell (WBC) count of the patients in JAK2 gene mutation group was higher than those in the wild type group [(9.5±4.7)×109/L vs (8.4±46.9)×109/L, P<0.05]. As for the patients in PV group, the platelet count of the patients in JAK2 gene mutation group was higher than those in the wild type group [(370.2±113.1)×109/L vs (264.8±63.9)×109/L, P<0.05]. The incidence of splenomegaly in MPN patients was 35.2% (43/122), and the incidence of splenomegaly in MF patients was 63.3% (19/30), and the incidence of splenomegaly in the patients in JAK2 gene mutation group in MF group (82.4%, 12/17) was significantly higher than those in the wild-type group (38.5%, 5/13) (P<0.05). The mutation rate of JAK2 gene in MPN patients is higher, and the mutation rate of JAK2 gene in PV patients is higher than that in ET and MF patients; JAK2 gene mutations in MPN patients are related to hemogram index; the incidence of splenomegaly is the highest in MF patients, and splenomegaly is related to the occurrence of JAK2 gene mutations in MF patients.