Abstract: Objective To explore the influence of pretreatment and moisturizing measures based on feedforward control on cleaning efficiency of metal instruments. Methods A total of 2 000 samples were obtained from 250 samples in 8 experiments. Every time after blood staining, 250 samples were randomly divided into groups A, B, C, D and E. Group A was processed with purified water, group B was processed with 1∶200 diluted multi enzyme cleaning solution, group C was processed with 1∶200 diluted alkaline cleaning agent, group D was processed with soaking moisturizing gel, and group E was processed with no moisturizing pretreatment. The results of visual inspection and occult blood test(OB test)were compared between the five groups after moisturizing pretreatment for 4 and 24 h. Results The qualified rates of visual cleaning of instrument surface in groups A, B, C and D were significantly higher than those in group E after 4 h of moisturizing pretreatment, and the qualified rates of visual cleaning and OB test of instrument inner wall in groups B, C and D were significantly higher than those in groups A and E(P<0.05 or P<0.01). The qualified rates of visual cleaning of instrument surface in groups A, B, C and D were significantly higher than that in group E after 24 h of moisturizing pretreatment, and the qualified rates of visual cleaning and OB test of instrument inner wall in group D were significantly higher than those in groups A, B and C(P<0.05 or P<0.01). Conclusion The foam enzyme pretreatment agent has the best cleaning effect after moisturizing. The alkaline cleaner and enzyme cleaner have better cleaning effect after moisturizing treatment - in a short time, and the cleaning effect of pure water moisturizing treatment is not good.