A method for plagiarism detection of multithreaded program based on a thread slice birthmark includes steps of: 1) monitoring target programs during executing, real-time identifying system call, and recording related information comprising thread IDs, system call numbers, and return values; then pre-treating the information for obtaining a valid system call sequence Trace; 2) slicing the valid system call sequence Trace, for generating a series of thread slices Slice identified by the thread IDs; 3) generating dynamic thread slice birthmarks Birth of all the thread slices of two programs; 4) respectively generating corresponding software birthmarks PB1 and PB2 of the P1 and the P2 ; 5) matching based on a max bilateral diagram for calculating a max similarity between the software birthmarks PB1 and PB2; and 6) determines whether the program is plagiarized or not according to an average value of the birthmark similarity and a given threshold ε.