Objective:To deepen the understanding of myelodysplastic syndrome/myeloproliferative neoplasm with ring sideroblasts and thrombocytosis (MDS/MPN-RS-T), and to improve the levels of precise diagnosis and individualized treatment.Methods:The clinical data and next-generation sequencing molecular cloning results of two MDS/MPN-RS-T patients who were admitted to the First People's Hospital of Chuzhou in October 2017 and November 2019 were retrospectively analyzed, and the related literature was reviewed.Results:Case 1 was a 76-year-old female. The mutation loads from high to low were DNMT3A, JAK2 V617F and SF3B1. After administration of hydroxyurea, this patient acquired amelioration in anemia, and the platelet count improved. The clinical course was indolent. Case 2 was a 66-year-old male, who was initially diagnosed with essential thrombocythemia but failed to acquire response after hydroxyurea treatment. MDS/MP-RS-T was diagnosed after comprehensive examination. The mutation loads from high to low were SF3B1, ASXL1, JAK2 V617F and SRSF2. Pancytopenia occurred after disease progression, and the JAK2 V617F mutation finally turned negative. Administration of erythropoietin and lenalidomide failed to improve the condition, but low-dose decitabine treatment (10 mg/d, 3-5 d, once a month) improved the hematopoiesis.Conclusions:The co-mutation of JAK2 V617F and SF3B1 has a suggestive effect on the diagnosis of MDS/MPN-RS-T, and dynamic next-generation sequencing is helpful to elucidate the molecular nature of clinical heterogeneity of the disease. Low-dose decitabine has a certain curative effect on MDS/MPN-RS-T.