Objective To study factors influencing the efficiency of ultrasonic cleaning of medical devices, and provide reference for rational improvement in methods and processes of ultrasonic cleaning of medical devices in hospital central sterile supply department. Methods Ultrasonic energy detection bottle and ultrasonic intensity detector were used to detect the ultrasonic efficiency, lumen type cleaning effect detection cards were used to detect the ultrasonic cleaning efficiency. Results There were significant differences between degassing group and non-degassing group in the average discoloration time of the energy bottle, the ultrasonic intensity and average cleaning qualified time of detection cards (P<0.05); differences between device regular placement group and stacking placement group was statistically significant (P<0.05); there was significant difference between single-layer placement group and double-layer placement group (P<0.05), there was no significant difference in the same detection site between single basket group and double basket group under the condition of the same number of layer (P>0.05). Among 4 kinds of detergent, brand A had the best cleaning efficiency and the fastest cleaning speed, but there was no significant differences in the average discoloration time of energy bottle and ultrasonic intensity detection (P>0.05). The best cleaning efficiency was achieved when the amount of detergent was 1:100 and the cleaning temperature was at 45℃. Enzyme activity of detergent was about 1 600 U within 2 hour of ultrasonic time, difference was not statistically significant (P>0.05). Conclusion Degassing, device placement, device loading mode, different detergent and cleaning temperature can all lead to the change of ultrasonic cleaning efficiency, only by selecting rational cleaning conditions can achieve satisfactory results of ultrasonic cleaning of medical devices.