Objective To evaluate the economics of azacitidine versus decitabine in the treatment of myelodysplastic syndrome(MDS)from the perspective of health system in China,and provide references for clinical drug selection.Methods A Markov model was constructed based on the data of a multi-center retrospective cohort study(NCT01409070),with a model simulation time limit of 10 years and the cycle period of 28 days.The quality-adjusted life years(QALYs)was used as health output index and incremental cost-utility ratio(ICUR)was calculated to evaluate the economics of azacitidine versus decitabine in the treatment of MDS.One-way sensitivity analysis and probabilistic sensitivity analysis were adopted to examine the robustness of the model simulation results.Results The results of basic analysis showed that compared with decitabine group,the total cost of azacitidine group reduced by 281 185.46 yuan and the utility increased by 0.17 QALYs.Azacitidine therapeutic regimen was the absolute dominance plan.One-way sensitivity analysis showed that progression-free survival state utility value,discount rate and decitabine cost had greater influence on the results.The results of probabilistic sensitivity analysis suggested that azacinidine therapy was always economical within the willingness to pay threshold range of 3 times Chinese per capita gross domestic product in 2021.Conclusion From the perspective of health system in China,azacitidine has more cost-utility advantages than decitabine in the treatment of MDS.