Background: Despite advances in microsurgical techniques of flap transfer, complex upper extremity trauma reconstruction remains a challenge for surgeons. This study aimed to present the outcomes in using flaps in the subacute reconstruction of complex upper extremity injuries. Methods: From July 2013 to December 2016, 35 patients ranging in age from 23 to 69 years with complicated upper extremity traumatic injuries were treated using flap reconstruction in subacute period. The number and causes of injury were 12 machine crush injuries, 18 machine strangulation injuries, two chainsaw accidents, two traffic accidents, and one incident of heavy bruising. Thirty-five patients underwent flap procedures, including 24 anterolateral thigh flaps (68.57%), five latissimus dorsi flaps (14.29%), and six lateral arm flaps (17.14%). Flap sizes ranged from 3 × 4 to 42 × 16 cm 2. The mean time of flap reconstruction was 14 days (range 5-29). During postoperative follow-up, flap appearance, sensory recovery, scarring and satisfaction were assessed. Results: The overall flap survival rate was 94.3%.Two flaps developed partial necrosis, both of which were later treated with skin grafting. Traumatic wound infections occurred in three patients. All upper limb injuries were completely covered. The follow-up periods ranged from 18 to 62 months with an average of 2.9 months. All skin flap textures were soft with varying degrees of pigmentation. Flap sensory recovery was S 1 in three cases, S 2 in eight cases, S 3 in 15 cases, and S 4 in nine cases. There were no donor site complications other than three cases with scar hyperplasia. Conclusions: The severe upper limb soft tissue defects still achieved satisfactory function and appearance with negligible complications and low amputation rates during the subacute period.