Objective:To discuss the method for establishing the rat models of irritable bowel syndrome(IBS)by chronic water avoidance stress(WAS)method,and to evaluate its feasibility.Methods:Thirty male Wistar rats were randomly divided into control group(n=10)and model group(n=20).The rats in model group were induced by WAS method for 1 h everyday,lasting for 10 consecutive days;the rats in control group underwent no interventions.After modeling,the general conditions and body weights of the rats in two groups were observed and recorded.The elevated plus maze(EPM)test was used to detect the percentages of the number of open arm entries(OE)and the time spent in open arms(OT)of the rats in two groups;the abdominal withdrawal reflex(AWR)test was used to assess the visceral sensitivity of the rats in two groups;electrocardiography was used to detect the heart rate variability(HRV)of the rats in two groups;electromyography(EMG)of the external oblique muscle was used to detect the colorectal pain sensitivity thresholds of the rats in two groups;multi-channel physiological signal recorder was used to monitor the slow wave frequency of the colon of the rats in two groups.Results:There were no death rats in both groups during the modeling period.After modeling,the rats in model group exhibited poor mental status,reduced spontaneous activity,hypoactivity,disordered and dull fur,irritability,and unclean anal areas;whereas,the rats in control group showed no significant changes in the mental state,spontaneous activity,fur,and perianal area.Compared with control group,the body weight of the rats in model group was significantly decreased(P<0.05).The EPM test results showed that compared with control group,the OE percentage and OT percentage of the rats in model group were significantly decreased(P<0.01).The AWR test results showed that 12 rats in model group scored≥3 points,indicating that the successful rate in creating the visceral pain models was 60%.Compared with control group,the low frequency(LF)signals and the ratio of LF/high frequency(HF)of the rats in model group were significantly increased(P<0.01),and the HF was significantly decreased(P<0.05).The EMG results showed that compared with control group,the coloretal pain sensitivity threshold of the colon of the rats in model group was significantly decreased(P<0.01),and the slow wave frequency of the colon was significantly increased(P<0.01).Conclusion:The WAS method for establishing the rat model of IBS effectively demonstrates the changes in behavior and mental state,increased the visceral sensitivity,accelerated colonic slow wave frequency,and autonomic nervous system imbalance;the WAS method can serve as an effective modeling approach for observing and evaluating the related drugs and interventions on treatment of IBS.