Distributed Denial-of-Service (DDoS) attacks seriously threat the servers in the Internet. Most of current research is focused on the detection and prevention methods at the victim side or the source side. However, defense at the innocent side, whose IP is used as the spoofed IP by the attacker, is always ignored. In this paper, a novel method at the innocent side has been proposed. Our detection scheme gives accurate detection results using little storage and computation resource. From the result of experiments, the approach presented in this paper yields accurate DDoS.