SpaceWire is a new bussing technique provided by European Space Agency. As the new bussing technique, SpaceWire enhances the functions of error detection and error recover［1］. In order to solve the problem of blocking in the net and reduce the SpaceWire delay［2］，SpaceWireD performs the timecode flowing in the net and schedule table. Aerospace has high requirements for the reliability of devices. Router is the indispensable component in the net，the reliability of the router affects the reliability of the net［3］. This text based on accomplishment of the SpaceWire router by modifying Dundee router IP Core applies the structure that one board with two routers, it uses the corporation between one of the reserved bits of timecode in SpaceWire and modeshift of the SpaceWire router to realize the hot backup function and enhance the reliability of the SpaceWire router. Finally, by using testbench to prove the function of modeshift,it can work properly, analysis and comparison prove that this scheme can enhance the reliability of the router.