For base timing-driven PathFinder router, it is found that the High-Fan-Out-Net routing spends around half of the time to insert the previous routed routing tree into routing resource node priority queue, but not all the nodes inserted are useful. In light of this finding, we proposed a pruning tree based priority queue initialization algorithm by just inserting the routing resource node which shares the same direction with next routing sink. For the High-Fan-out Net benchmark, results show our algorithm can shorten the initialization time by 5.23 times, and achieve 1.55 times speedup with almost the same quality of result.