Objective To introduce the method of reconstructing posterolateral complex injury of the knee with the autogenous middle 1/3 of biceps femoris tendon and gracilis and evaluate its short-term outcome. Methods There were 21 cases of posterolateral complex injury of the knee reconstructed with the middle 1/3 of biceps femoris tendon and gracilis from January 2003 to December 2006. There were 13males and 1 female at age range of 18-49 years ( mean 34.3 years). The reconstructed ligaments included popliteal tendon, lateral collateral ligament and poplitrofibular ligament. An autogenous folded gracilis tendon was extracted and placed through trastibial bony tunnel from anterolateral to the posterior condylar of the tibia to reconstruct the popliteal tendon. An autogenous folded middle 1/3 of biceps femoris tendon was fixed in the isometric bony tunnel of the femoral lateral condyle. The anterior half was used to reconstruct the lateral collateral ligament, and the posterior half to reconstruct the poplitrofibular ligament. The posterolateral stability of the knee was evaluated mainly through examination varus instability of knee and external rotation range of leg. Results All cases were followed up for average 26 months (6-24months). Lysholm score of the knee was (43 ± 2) points preoperatively and (90 ± 3 ) points half year after operation, with significant improvement. Conclusions PCL injury may result in functional deficiency of the injured extremity. While the autogenous middle 1/3 of biceps femoris tendon and gracilis can yield a stable knee with good function, mini-trauma and satisfactory clinical results in reconstructing the posterolateral complex of the knee joint.