Abstract： Objective To explore the methods of reducing bacterial microbial contamination of the water storage tank system in department of stomatology,and reduce the occurrence of iatrogenic infection in department of stomatology.Methods The water storage tank and distilled water were replaced with conventional methods every 24 hours in control group,while the storage tank water system in observation group were carried on the flushing disinfection with oxidized electric potential water per person.The number of bacterial microbial contamination of the water storage tank system in two groups was studied and compared. Results The qualified rate of water samples from 60 oral water system in control group was 66.67％,and that in observation group was 100％,byx2 - inspection P ＜ 0.01. Conclusions The bacterial microbial contamination of water storage tank system in department of stomatology is serious,We should pay more attention to it and strengthen the management.Using oxidized electric potential water for disinfection of water storage tank system,which can obviously reduce the microbial quantity,is an effective method of controlling bacterial microbial contamination in department of stomatology.