The hardware interface and software design of MPEG－2 decoder card based on PCI local bus is presented. By analyzing program information of the multi－program MPEG－2 transport stream, the user could pick out one set of program to decode and display. The encoded data is sent to the decoder card through PCI local bus. The data exchange among memory, PCI bus, and hard disk were implemented by multi－thread processing in the software. The software design architecture is presented.