Abstract: This paper discusses the software plagiarism detection technologies which are based on text, token and abstract syntax tree, and especially discusses the technology based on abstract syntax tree (AST) in detail. At the same time, according to the study of software plagiarism detection applications, this paper mainly introduces the architecture of software source code homologous detection system and some kinds of key functional modules. For a demonstration of the feasibility on the proposed algorithm, this paper makes a deep analysis and evaluation of the source code homologous detection system.