Abstract: Objective To compare the retention effect of activators and Hawley retainers in retention period of the mandibular retrusion patients after fixed orthodontic treatment. Methods 40 adolescent patients who had finished their fixed orthodontic treatments were randomly divided into two groups,respectively wearing activators or Hawley retainers.Cephalometric analysis and difference in model overjet,overbite proceeded forthwith and one year later.All data were subjected to paired ttest and Wilcoxon rank sum test. Results Patients wearing Hawley retainers indicated more retrusion tendency compared with the activator group. Conclusions Activators serves as a better choice for patients with mandibular retrusion in retention period which can better prevent recurvence of mandibular retrusion.