The invention provides a software interface method for a multimedia playing terminal based on internet. A playing system consists of a playing terminal, a server and a control center computer. The method comprises the following steps: when a terminal logs on, initial information is transmitted to the server, and the initial information includes machine name number, IP address, type, installation address, name of a person in charge, telephone number and local media file list; when the terminal works, the information of work status and work log is transmitted to the server; before the terminal plays, the information of tasks is read from the server, and the tasks include deleting or downloading media file on fixed disk, playing at definite time according to a playing list, and inter cutting according to special requirement. The software interface method is applicable to any network multimedia playing system with the server, a database and a multimedia playing terminal with a network interface.