Abstract: To reduce the running time and improve the efficiency of string similarity detection， an improved string similarity detection algorithm is proposed utilizing the improved KR algorithm and GST algorithm. Using  students' homework source code as the experimental data，the performance of the improved algorithm is tested， and the results show that the improved algorithm can achieve the duplicate check result similar to GST in less fewer comparison times.

Key words: string, similarity, approximate matching, greedy pattern matching algorithm, Karp-Rabin algorithm