With the rapid development of Internet, mobile networks and high-performance networking technology, QoS multicast routing in networks with uncertain parameters has become a very important research issue in the areas of networks and distributed systems. This is also a challenging and hard problem for the next generation Internet and high-performance networks. It attracts the interests of many people. This paper discusses the multicast routing problem with multiple QoS constraints in networks with uncertain parameters, and describes a network model that is suitable to research such QoS multicast routing problem. The paper mainly presents QMRGA, a multicast routing policy for Internet, mobile network or other high-performance networks, that is based on the genetic algorithm, and can provide QoS-sensitive paths in a scalable and flexible way, in the networks environment with uncertain parameters. The QMRGA can also optimize the network resources such as bandwidth and delay, and can converge to the optimal or near-optimal solution within few iterations, even for the networks environment with uncertain parameters. The incremental rate of computational cost can close to polynomial and is less than exponential rate. The performance measures of the QMRGA are evaluated using simulations. The results shows that QMRGA provides an available approach to QoS Multicast routing in networks environment with uncertain parameters.