The Von Neumann Model on national economical system is investigated. A new discrete-time input-output model on national economic system based on the classic Von Neumann Model is provided and the stability of this kind of model is researched. This new system belongs to the singular system. By the new mathematic method, this singular linear system will not be converted into the general linear system. Finally, a sufficient stability condition under which the discrete-time singular Extended Von Neumann Model is admissible is proved.