To solve the problem of out-of-sight communication in remote ground-air communication, an out-of-sight air-ground communication scheme is proposed, which is relayed by multi-elliptical orbits small satellites. At first, orbit parameters of small satellites are designed and average coverage rate of target area is certified 99.41% by using medium ellipse orbit constellation which consists of 4 satellites. Then work principle and link propagate characteristic of out-of-sight air-ground communication system is studied and link transceiver parameters are designed on that basis. The simulation results show that the use of the proposed system in communication is without distance limit, and the system has the advantages of good communication effect, good anti-destroyed performance and low cost.