Objectives To explore the isometricity of grafts in PCL（posterior cruciate ligament）double-bundle reconstruction under femoral tunnel shifting condition . Methods Knee specimens from ten fresh frozen cadavers were used. PCL were divided into anterolateral bundles (ALB) and posteromedial bundles (PMB) to the insertion footprint .The anterior , posterior , proximal , distal and central points of the two bundles’ femoral attachment site were respectively anchored to the middle of the PCL’s tibial attachment site by the trial wires. Changes in length of the intra-articular part of the wires were recorded while the knee was flexed from 0°to 120°. Results The length changes in every points were compared. All of the maximal length changes of ALB’s proximal, posterior points and PMB’s proximal points were not greater than 2mm. No significant difference between the length changes of ALB’s proximal point and posterior (P=0.864＞0.05) . Conclusions The femoral tunnel for the PCL double-bundle reconstruction should be located as follows: ALB should be at the middle point of upper edge of femoral attachment site (proximal point), while PMB at the middle point of femoral attachment site (proximal point).