Objective　To provide the anatomical basis for the design of the tripaddle flap on the posterior interosseous artery (PIA).　Methods　Eight cadaveric forearms were used for this study. A line was drawn representing the axial line from the lateral epicondyle of the humerus to the radial side of the ulnar styloid on the dorsal forearm. The dissection was applied in distal three segments for the peforators of the PIA. The following contents were investigated: the position and the number of the perforators; the course of the perforator; the length of the pedicle of perforators dissected from the underneath layer of the deep fascia and the superficial layer of the deep fascia. One cadaveric was used to imitate the harvest tripaddle PIA flap. Results　The PIA gave off 4 to 7 perforators, and the range number of perforators in segment Ⅰ,Ⅱ and Ⅲ was from 2 to 4, 2 to 3, and 1 to 3, respectively. The range of the pedicle length of perforators dissected from the underneath layer of the deep fascia was from 0 to 0.6 cm, 0.2 to 1.2 cm, 0.5 to 1.8 cm, respectively. The range of the pedicle length of perforators dissected from the superficial layer of the deep fascia was from 1.2 to 2.7 cm, 1.2 to 4.5 cm and 1.8 to 4.5 cm, respectively.　Conclusion　The perforators at the different segments of the PIA can be used to design the tripaddle flaps.