Abstract: With the development of space technology, components on satellites and spacecrafts are becoming more and more complicated, there is a need of more simple applicable redundant scheme and reliability analyzing method for engineering application. A new approach for a special kind of redundant system is proposed, which is applied in redundant inertial attitude reference system on satellites. It is a new redundant scheme that takes K out of N redundant system and cold store redundant system. It is proved that scheme is ready for engineering practice in theory.