Petrological and mineralogical characteristics of the granulites from the Qiongzhong complex were studied in this paper, and the temperatureand pressure conditions for the formation of the granulites were estimated by avariety of geothermometers and geobarometers. The results show that the granulites belong to typical low-pressure granulites formed in an environment of high_temperature and low_pressure (low p/T), with peak temperature being 824±15℃ and corresponding pressure lower than 0.5 GPa. The granulites were cooled during late retrograde reaction which terminated at the temperature of 705℃, withthe corresponding pressure near the peak. Therefore, the p-T path of the low-pressure granulites from the Qiongzhong complex was clockwise, composed of two phases of heating during early slow decompression and nearly isobaric cooling (IBC) during late retrograde reaction. Combining characteristics of the p-T path of the granulites with the features of relatively weak deformation and regional tectonic setting，it is considered that the low-pressure granulites from the Qiongzhong complex were formed in an environment of crustal extension. The possible mechanism is as follows: because the crust was thinned by extension, the crustal heat flux was raised by the introduction of magmas generated through decompression of the asthenosphere, and then prograde metamorphism took place in theoverlying rocks (including crystallized magma); afterwards the geothermal gradient disturbed by extension was restored to normal gradient and, as a result, theclockwise p-T path composed of two phases of heating during decompres-sion and nearly isobaric cooling (IBC) was produced.