A music search engine is invented to find a desired song in the database by comparing the melodies. This invention comprises two major parts: a client-end and a server-end. The client-end converts various input formats into a note sequence and sends it to the server-end engine. The server-end then compares the note sequence with the melodies in the database and finds the closest match. This invention enables us to search music by its melodic content instead of titles, lyrics or other annotated information. Moreover, this invention tolerates inaccurate inputs so that even less skilled people can hum to the system with inaccurate melody and find the target song.