ObjectiveTo improve the cleaning quality of reusable medical instruments continuously through root cause analysis, reduce healthcareassociated infection(HAI) and the wear and tear of instruments.MethodsThe major factors influencing the cleaning quality of instruments were analyzed and clarified by fishbone diagram, continuous quality improvement was carried out based on 5 terminal factors, the rate of rusting, stain, repeated cleaning, damage, and clinical department satisfaction before and after the implementation of continuous improvement were compared.ResultsThe qualified rate of instrument clean increased from 94.24% before implementing measures to 97.60% after implementing measures, the rate of rusting, stain, repeated cleaning, damage decreased from 3.39%, 2.37%, 5.76%,and 2.08% to 1.55%, 0.85%, 2.40%, and 0.48% respectively, there were significant difference among different groups(all P＜0.001); the score of satisfaction rate to central sterile supply department elevated from(93.87±3.87) before implementing measures to (98.08±0.59) after implementing measures（t=6.80，P＜0.001）.ConclusionRoot cause analysis is important in improving cleaning quality of reusable instruments continuously, as well as reducing HAI and the wear and tear of instrument, it can save medical cost.