This article proposes a clone detection method based on a program characteristic metrics. Though analyzing the syntax and semantic characteristics of vulnerabilities, this detection method abstracts certain key nodes which describe different forms of vulnerability type from syntax parser tree, and expands four basic types of code clone to auxiliary classes. The characteristic metrics of the code then is finalized by obtaining the number of key nodes which are calculated via scanning corresponding code segment in the syntax parser tree. The clone detection based on a characteristic metrics creates basic knowledge base by extracting partial instances of open vulnerability database, and precisely locates the vulnerability codes by performing cluster calculation on the same codes responding to multiple types of code clone. Comparing with the detection method based on single characteristic vector, the proposed method produces more precise description about vulnerability. This detection method also offers a remedy to the drawbacks of formal detection method on its vulnerability type covering ability. Nine vulnerabilities are detected in an android-kernel system test. Testing on software of different code sizes shows that the performance of this method is linear with the size of the code.