Abstract: Delay Tolerant Networks (DTNs) are one of the emerging mobile wireless networks that cannot set up the end-to-end communication path between the source and destination node pairs in most of time. Due to the main characteristics of intermittent connectivity and long delay, the traditional routing algorithms for the Internet and Mobile Ad-Hoc Networks do not perform well in DTNs. In this paper, we propose an improved Spray&Wait Routing Algorithm Based on Node Performance (NPSW), which is mainly evaluated by the number of encountered nodes in a period. In addition, we also design a utility metric to select next hop node(s) with the consideration of the combination of encountering count to the destination node and the last contact time. Extensive simulations have been conducted and the results show that our proposed method can achieve a higher bundle delivery ratio and incur much lower communication overheads. As compared with other existing DTN routing protocols, the results also indicate that the NPSW scheme achieve a better routing performance.