SpaceWire is a standard for high-speed links and networks between spacecraft components, which was invented for better, cheaper, faster on-board data handling in spacecraft. SpaceWire is being widely used on many space missions by ESA, NASA and JAXA, and is expected to be used in future satellite development programs in Korea. For flexible and efficient application of SpaceWire, it is necessary to secure the related technologies. This paper describes the development, implementation and test of a SpaceWire link interface, which will be incorporated in MMU(Mass Memory Unit) of STSAT-3(Science & Technology Satellite-3).