A file decoding method uses a master server to decode multimedia files. The method records statuses of a plurality of slave servers in a status table, receives a decoding request to decode the multimedia file from a web server, and selects one slave server from the status table to process the decoding request by the master server. The method further sends an Internet protocol (IP) address of the selected slave server to a web browser by the web server, sends a decoding command to the selected slave server by the web browser, decodes the multimedia file by the selected slave server, and transmits decoded data of the multimedia file to the web browser.