Focusing on the routing selection of end-to-end key agreement in Quantum Key Distribution (QKD) network, an optimal routing selection algorithm of end-to-end key agreement based on the Dijkstra algorithm was designed. Firstly, the unavailable links in the QKD networks were eliminated based on the strategy of choosing the available paths. Secondly, based on the strategy of choosing the shortest paths, the Dijkstra algorithm was improved to find out all the shortest paths with the least key consumption. Finally, according to the strategy of choosing the optimal path, the optimal path with the highest network service efficiency was selected from the shortest paths. The analysis results show that, the proposed algorithm solves the problems such as the optimal path is not unique, the best path is not the shortest, the optimal path is not optimal, and so on.The proposed algorithm can reduce the key consumption of end-to-end key agreement in QKD network, and improve the efficiency of network services.