Abstract: Objective: To analyze the clinical characteristics and gene mutations of juvenile myelomonocytic leukemia (JMML). Methods: The clinical data of children diagnosed with JMML from January 2013 to December 2019 in the Department of Pediatric Hematology and Oncology of the First Affiliated Hospital of Zhengzhou University were retrospectively analyzed. Results: Among the 19 children with JMML, there were 14 males and 5 females. The age at the time of visit was (16.8±16.4) months old, and 5 patients were older than 2 years old. The most common symptoms at the time of the visit were fever and pale skin. All 19 cases had hepatosplenomegaly, with the maximum of 12 cm and 13 cm under the costal margin of the liver and spleen, respectively. Lymphadenopathy was found in 11 cases, and the common sites were neck and axilla. The WBC, monocyte and PLT in peripheral blood were 37.3×109·L-1, 7.2×109·L-1 and 32×109·L-1 , respectively. Four children had higher hemoglobin F (HbF) level than normal. Viral IgM was positive in 12 cases, with CMV being the most common (8 cases). The median percentage of primordial granulocytes in the bone marrow of 15 children was 1.2% (0-6.4%). Chromosome karyotype analysis was performed in 7 cases, and chromosome 7 monosomy was found in 2 cases. The BCR/ABL1 fusion gene test was negative in 15 children. The number of patients with KRAS, NF1 and NRAS gene mutations was 4, 2 and 1, respectively. Fourteen cases gave up treatment. Five patients were followed up, and as of June 1, 2020, three died and two survived, with a median survival time of 2 (1-34) months. Of the two surviving children, one was treated with chemotherapy and awaited hematopoietic stem cell transplantation, and the other one was transformed into acute myeloid leukemia M5, which was treated with chemotherapy according to the treatment regimen of acute myeloid leukemia. None of the 3 deaths was treated with chemotherapy, and the survival time was 1 to 2 months. Conclusion: In this study, KRAS gene mutations were common in JMML children. Children with untreated JMML had shorter survival time.