Abstract: In order to improvethe transfer efficiency while at the same time reduce the network delay and network cost in delay tolerant network(DTN), a DTN routing algorithm based on probabilistic delay, namely PD, is proposed. The link state algorithm is referenced in PD. Transfer delay, connectivity between nodes and historical factors are fully taken into consideration. Through simulative analysis, PD is found to be able to achieve better performance than CAR and epidemic routing in network environment with relatively long network transfer delay.