Objective To assess the outcome of orthodontic treatment with upper jaw or upper and lower jaw extraction for Class Ⅱ division 1 malocclusion using the peer assessment rating（PAR） index. Methods 28 patients with Class Ⅱ division 1 were extracted two first premolars or second premolars of upper jaw, and 24 patients were extracted four premolars of upper and lower jaw N. The PAR was applied on pre-and post-orthodontic treatment dental casts for the fifty-two cases. Results The upper and lower jaw extraction groups had significantly higher initial PAR scores and the weighted PAR total scores（P0.05）. Conclusion The upper and lower jaw extraction cases showed more severe dental displacement. Both treatment can acquire successful results.
