The invention provides a self-adaptive three-dimensional transmission method and system in a space-ground integrated information network, and the method comprises the steps: S1, calculating the transmission cost of each path between a preset transmitting end and a receiving end on four layers of networks based on a space-ground integrated information network system; s2, obtaining a cost minimum path on each layer of network based on the transmission cost of each path, obtaining a routing table item on each layer of network based on the cost minimum path on each layer of network, and forwarding the data packet through the routing table item; s3, according to the transmission capability of each layer of network, dynamically distributing the traffic weight on each layer of network, and continuously detecting the load on each layer of network to ensure the dynamic load balance in the transmission process; and the four hierarchical networks comprise a GEO satellite network, an MEO satellite network, an LEO satellite network and a ground Internet. According to the invention, the data transmission is adaptively distributed on different network levels, the resource utilization rate of each layer is fully improved through the cooperation of each layer of network, and the load balance in the space-ground integrated whole network range is ensured.