Abstract:A telemetry relay system based on medium-high altitude unmanned aerial vehicle is proposed to solve the difficulty and high cost of full range telemetry for low altitude long range moving targets by analyzing the characters of land, sea and air based measure. The system is used toghter with land, and sea based telemetry station to achieve the track for low altitude long range moving targets. The system principle compose and working mode are designed, and system general design is briefly analized, and the key technics such as unmanned aerial vehicle platforms, phased array antenna design, relay transmission mode, mricro-system technique, and phased array antenna track and so on, are analized.