The instrument landing system on decimeter wave band is first analyzed in a systematic way. The forming of its navigation information is researched deeply. The characteristics of the system are pointed out and the main technology terms are defined. At the same time, the realization means of the instrument landing system on decimeter wave band are presented. In the end, the technology scheme of producing navigation signal and building radiation pattern is given, which provides a theoretic reference for developing the instrument landing system on decimeter wave band independently.