Abstract: Objective:The microbial inactivation and quality changes of fresh cut lettuce treated with cold plasma activated water were investigated in this paper. Methods:PAW was produced by dielectric barrier discharge at 35,55 and 75 kV for 5 min. All samples were washed with PAW for 5 min and stored for 10 days(4 ℃,85% RH). The microbe(total aerobic plate count and coliform group),as well as the weight loss rate,color,ascorbic acid,chlorophyll and polyphenol oxidase activity of the samples were tested every two days. Results:The sterilization effect of PAW on lettuce significantly increased with the increase of treatment voltage(P<0.05).At the end of storage,the total colony count and coliform count of the 75 kV treatment group were 1.15 lg(CFU/g)and 1.38 lg(MPN/100 g)lower than the control group,respectively. Meanwhile,PAW treatment could effectively decrease the PPO enzyme activity and color change of samples(P<0.05),but there was no significant difference between different treatment groups(P>0.05).The 35 and 55 kV treatments had no significant effect on the ascorbic acid and chlorophyll content of the samples,but when the voltage increased to 75 kV,it would have an adverse effect. Conclusion:The optimum treatment voltage of PAW for keeping fresh of fresh cut lettuce was 55 kV.