Aimed at the problems

such as low key exchange efficiency and large meaningless consumption of secret key materials

when the existing routing schemes for trust relaying QKD (quantum key distribution) network used in the wide-area environment

a hierarchical routing scheme which is suitable for wide-area QKD network was designed. This routing scheme divided the QKD network into multiple routing areas

built a hierarchical network by topological aggregation and designed a cross-domain routing algorithm based on the principle of the lowest layer matching. Then the hop number in the routing path is decreased

and the efficiency of key exchange and the utilization rate of secret key materials ware increased. At last

the simulation results shows that our hierarchical routing scheme can increase about 77.6% utilization rate of secret key materials and reduce service delay by half compared with the existing routing schemes which just relaying secret key hop by hop in a single layer.