Abstract: The development of architecture of Avionics system,its architecture today,and its limifations are described briefly. The commercial network standard SCI is also introduced briefly. A bottom protocol and performance of inter linkage standard of SCI/RT which is established for real time application is described in detail. That the SCI/RT is the key technology and prefevred standard of future military Avionics system, is pointed out and great importance should be attached to it and its research quickened.