Abstract: The paper investigates the QoS routing problem with uncertain network condition, including MP(Most Probable Path), OP(Optimal Partition) and OP-MP(Optimally Partitioned MP). The question MP is studied when density function of the link delay is continuous and an algorithm for a special case that the link delay has normal distribution is proposed. For question OP and OP-MP, two cases of QoS partition are given: Case I optimizes the product of the probability that all the links of the path satisfy the partitioned constraints, while the case II maximizes the minimum of them. The two cases are analyzed and the algorithms are given.