Objective To investigate the variation of supratrochlear vein and its relationship with supratrochlear artery and to provide anatomical basis for the reduction of congestive necrosis of paramedian forehead flap in the reconstruction of nasal defect. Methods Twenty sides of 10 antiseptic head specimens were anatomized macroscopically and microscopically. Using the horizontal and anterior median l ine of supraorbital rim as X and Y axis to locate supratrochlear vein and artery, the angles between the supratrochlear artery and vein and the supraorbital rim were detected, and the distances from the supratrochlear artery and vein to the anterior median l ine on the horizontal l ine of supraorbital rim were measured. Results The distance from the supratrochlear artery and supratrochlear vein to the anterior median l ine on thehorizontal l ine of the supraorbital rim was (16.2 ± 2.1) mm and (9.7 ± 3.1) mm, respectively, indicating there was a significant difference (P lt; 0.05). The angle between the supratrochlear vein and artery and the supraorbital rim was (83.3 ± 6.4)° and (80.5 ± 4.2)°, respectively, indicating there was no significant difference (P gt; 0.05). Two asymmetric supratrochlear veins were observed around the area of anterior median l ine in every specimen, one was far from the anterior median l ine (group A) and the other was close to or even on the l ine (group B). The distance from the supratrochlear veins to the anterior median l ine on the horizontal l ine of the supraorbital rim was (11.0 ± 1.9) mm in group A and (7.9 ± 3.2) mm in group B, showing there was a significant difference between two groups (P lt; 0.05). For all the specimens, the supratrochlear vein ran laterally along the medial anterior median l ine of the supratrochlear artery (one side was just on the anterior median l ine). The distance from the supratrochlear veins to the supratrochlear arteries on the horizontal l ine of the supraorbital rim was (6.6 ± 3.2) mm, (5.5 ± 2.0) mm in group A and (7.9 ± 3.9) mm in group B, indicating the difference between two groups was significant (P lt; 0.05). Conclusion The pedicle of the paramedian forehead flap should be wide enough (1.5-2.0 cm), the lateral boundary of the pedicle should be the supratrochlear artery while the medial boundary should be the supratrochlear vein.