Without modifying the flight control law and maintaining its quality under the premise of the original flight quality, realize UAV super low altitude flight of certain type small UAV by exploiting its potential. Use radio altimeter to acquire actual height of UAV relative sea level. Design data collection switch box, intercept the original air pressure height, and combine it with the radio altimeter data and apply combination in UAV super low altitude flight control. Intercept telemetry information, radio altimeter value will replace non critical data, and use the original control channel sent to the ground station, the ground command operator issues instructions and verify it by actual flight. The results show that the UAV super low altitude flight was realized by these measures. It is concluded that the method is feasible and effective, and suitable for applications part of performance improvement and function expansion for the purchased UAV.