The airspace communication network based on spacecraft has a wide range of applications in regional information enhancement and emergency communication. In this paper, a routing algorithm for congestion degree detection of multipath routing (CD_AOMDV) is proposed. The method of combining the whole congestion degree detection and local congestion degree detection before service initiation is adopted. Timely and accurate judgment of the congestion degree reduced the loss rate of the hot nodes, so the average packet loss rate reduced. Simulation results show that compared with the traditional AOMDV protocol, the CD_AOMDV proposed in this paper has reduced the packet loss and improved delay performance, which is more suitable for the airspace communication network.