Abstract: Traditional network routing algorithms can not quickly perceive link changes and make optimal decisions in QKD network. In view of this, a multi-path routing algorithm for QKD network based on KSP is designed. The algorithm took the remaining key amount as the initial link cost to calculate the first K shortest paths. At the same time, it introduced the important factor of key freshness, measured the key freshness by regularly querying the key production time difference, and selected an optimal path by comparing the average key freshness of K paths. Experimental results show that the algorithm can solve the problems of unbalanced key consumption and interruption of key distribution in a single path, and effectively improve the success rate of key distribution and the uniformity of link key consumption.