syntax tree, High-level fuzzy petri net.Abstract. Students, who majored in computer science, are required to design and code in a variety of programming languages. However, many students submit the source code assignments they get from the Internet or friends with no or little modification. This paper proposes a novel method of detecting the source code plagiarism by using a high-level fuzzy Petri net (HLFPN) based on abstract syntax trees (AST). The experimental results indicate that we are directed to make better determination to detect the code plagiarism.