Abstract. The distributed adaptive routing is the typical routing algorithm that is used in the current Internet. The path cost of the least delay (LD) path is relatively more expensive than that of the least cost (LC) path, and the path delay of the LC path is relatively higher than that of the LD path. In this paper, we propose an effective parameter that is the probabilistic combination of cost and delay. It significantly contributes to identify the low cost and low delay unicasting path, and improves the path cost with the acceptable delay.