Objective To detect the expression of MMP-2 of posterior cruciate ligament (PCL) tissue after anterior cruciate ligament (ACL) injury. Methods The rat knee injury apparatus designed by our lab was used to injure ACL. Then, the expression of MMP-2 in PCL was detected at ex-vivo level with zymography. Results The expression of MMP-2 in PCL cultured supernatant fluid increased in a time dependent way after ACL injury. Conclusion PCL contributed to the accumulation of MMP-2 in the joint fluid after acute ACL injury.