Objective To explore the influence of femoral tunnel placement on the isometry of grafts in the reconstruction of posterolateral corner of the knee (PLC). Method Knee specimens from 9 frozen human cadavers were used in the study. Five points of femoral attachment sites, including the central, proximal, distal, anterior and posterior points, were selected as femoral test points for both lateral collateral ligament（LCL）and popliteus tendon（PT）. The fibular/tibial attachment sites of LCL, PT and popliteofibular ligament（PFL） were connected to the corresponding 5 test points using the brass wire, respectively. Changes in distance between each pair of fibular/tibial and femoral points were measured during the passive knee flexion extension test (0°~90°). Results The maximal changes of distances between the LCL’s anterior, distal points and LCL’s fibular attachment site were not greater than 3 mm, and there was no significant difference between these two points; the maximal change of distance between the PT’s anterior point and PFL’s fibular attachment site were not greater than 3 mm. All of the maximal changes of distances between the PT’s 5 test points and tibial point of musculotendionous junction were greater than 3 mm. Conclusions Under the condition of fibular tunnels locating at center points of LCL and PFL attachment site, the femoral tunnel should be located at the anterior edge of LCL’s attachment site (anterior point) for LCL reconstruction, and at the anterior edge of PT’s attachment site (anterior point) for PFL reconstruction.