Objective To observe the efficacy and safety of flumatinib conversion in chronic myelogenous leukemia-chronicphase(CML-CP)patients with suboptimal TKI response or intolerance.Methods Patients who did not have the best response or intolerance to first-line imatinib,dasatinib,and nilotinib and switched to flumatinib(600 mg/d)from February 2020 to August 2022 were collected from 5 hospitals from Chongqing and affiliated hospitals of North Sichuan Medical College.The efficacy and safety of flumatinib were observed.The optimal response rate,major molecular response(MMR),cumulative complete cytogenetic response(CCyR)rate,cumulative MMR rate,cumulative deep molecular response(DMR),progression-free survival(PFS),event-free survival(EFS)and adverse reactions in 3,6 and 12 months after treatment were observed and analyzed.Results A total of 100 patients with CML-CP were enrolled,with a median follow-up of 18(3～36)months.The optimal response rate was 92.6％(88/95),94.4％(85/90)and 92.9％(79/85)respectively,at 3,6 and 12 months after treatment.Till August 20,2023,the cumulative CCyR and MMR rate was 98.0％(98/100)and 81.9％(77/94),respectively,the median time to reach CCyR and MMR was 3 months,and cumulative DMR rate was 51.0％(51/100).PFS rate was 100.0％(100/100)and 1-year EFS rate was 85.6％(75/90).The most common non-hematologic adverse reactions of flumatinib were diarrhea and abdominal pain(7.0％),followed by renal dysfunction(6.0％)and musculoskeletal pain(2.0％).The main hematologic adverse reactions were thrombocytopenia(12.0％),anemia(6.0％)and leukopenia(2.0％).Conclusion Flumatinib has better MMR and DMR and is well tolerated in CML-CP patients with TKI resistance or intolerance.