Objective To improve the harvesting techniques of anterolateral thigh perforator flap, and to reduce the operation time. Methods Between January 2008 and June 2015, 400 patients undergoing repair with anterolateral thigh perforator flap were included to analyze the technical factors, including 370 cases (92.5%) obtaining primary healing and 30 cases (7.5%) receiving re-exploration. Combined with the literature, a modified flap dissection was made: reverse tracing and sequential dissection of the descending branch of the lateral circumflex femoral artery. Between June 2015 and June 2016, the modified free anterolateral thigh perforator flap was used in 100 cases. Of 100 cases, 76 were male and 24 were female, aged from 11 to 71 years (mean, 35.6 years). The wound size ranged from 8 cm×5 cm to 23 cm×9 cm. The time between injury and surgery ranged from 5 to 31 days (mean, 14.3 days). Results The operation time of modified flap dissection was reduced to (30.1±19.3) minutes from (85.0±30.2) minutes (unmodified flap dissection). Postoperatively, 94 flaps survived uneventfully, and incision healed by first intention. Six flaps received re-exploration surgery because of vascular compromise; the flap survived after removal of thrombosis in 4 cases of vein thrombosis; the flap necrosed in 2 cases of vein and artery thrombosis, and skin grafting was performed. Ninety-four patients whose flaps survived were followed up 3-12 months (mean, 6.3 months); the flaps had good color and appearance, and second stage operation was performed to make the flap thinner in 21 cases. Conclusion Improved harvesting technique of free anterolageral thigh perforator flap could decrease surgery time and difficulty in dissection.