The Quality of Service (QoS) requirements for a connection set-up includes a wide range of parameters. There are two major challenges as follows: the first one is to find a path that satisfies all the QoS requirements, which is an NP-complete problem, if the number of additive QoS parameters is beyond two. The other is inaccurate information in network routing that is an unavoidable problem. It is essential to properly treat and express the imprecision and the uncertainty of the QoS constraints. QoS routing problem has received much attention by researchers. In particular, some researcher developed efficient selecting path algorithms for connections with multiple additive QoS constraints by fuzzy theory.