Objective To investigate the effect of dexmedetomidine on delirium of elderly patients after artificial joint replacement. Methods 60 patients in ICU after artificial joint replacement were randomly divided into control group (30 cases) and experimental group (30 cases) from 2015 July to 2016 July. The experimental group was treated with intravenous infusion of dexmedetomidine, while control group was given the same amount of physiological saline. Delirium was observed postoperative 1-3 days in both groups, and condition assessment for consciousness was evaluated. Results The incidence of delirium (2/30,6.6%) in experimental group was significantly lower than control group (8/30,26.6%). Conclusion Dexmedetomidine can reduce incidence of deliriumthe in elderly patients after artificial joint replacement.