Objectives: For treatment of Class II molar relationship and anterior teeth exiting mild and moderate crowding. Molar distalization methods were often used in clinic, for needed spaces. American orthodontist, Greenfield introduced a method for upper molar distalization . However, there are few reports the results about GMD in our county. This article mainly concerns about clinical results for using GMD technique. Methods: 20 cases, (male 8, female 12) aged from 11.6~16.8 with Class II anterior crowding and/or mild protrusion were chosen in this clinical study. First promolars and molars fixed bands and the necessary attachments and lingual and buccal in dentition used Ni-Ti coil-springs transferring 200 g magnitude forces for each side pushing molar distalization. In order to enhance the anchorage, Nance-Palatal accrylical pad was connected the appliance. For evaluation the results of GMD, cast models and lateral cephalemetric in pretreatment and posttreatment were measured and analyzed. Results: All cases have been got needed spaces by means of GMD, the average duration was 4.3 months for molar distalization period. Average distance of molar distalization was 5.8mm (maximum 8.5, minimum 4.0mm P<0.001). Anterior teeth appeared mild proclination because lose anchorage, but first premolars and molars were no tipping significantly (P>0.05). Lateral cephalemetric also show no significant changes on hard-tissue, only with mild proclination in anterior teeth when first premolar and molar were be pushed distalization. Conclusions: GMD technique is a quick and effective method for pushing molar backward to resolve anterior crowding and the same time making molar relationship from Class II become Class I. It is important that the manner of molar distalization exhibits bodily one's, and no rotation.