Objective: To investigate the impulsivity of SHR (spontaneous hypertensive rat, the animal model of attention deficit/hyperactivity disorder), and compare it with the WKY (Wistar Kyoto Rats).Method:The experiment was carried on in the standard Campden instrument operant chambers, the animals were 22h deprived of water. A long Variable Interval Schedule was used and the stable documents of the last ten days were analyzed.Result:There was no significant difference of the reinforcement between SHR and WKY rats. The short inter-response times (IRTs) of SHR were much higher than that of WKY rats. There was no significant difference of short IRTs of the two groups among the three same segments of the experiment.Conclusion:The impulsivity of SHR is more obvious than WKY rats. It will be helpful for the biological research of ADHD.