The development status of radar and its countermeasures are mainly analyzed in this paper, the importance and necessity of that developing stealthy ability of weapon system are presented and the advantages and disadvantages of various stealthy techniques are compared. From the point of narrow stealthy, a kind of new system "the stealthy radar" is proposed and its usefulness and basic principle are elaborated. The communication concept is applied to the radar system, and a reference for forming the new weapon equipment which has the stealthy ability is provided.