Aiming at resolving the problem of Class of Service (CoS) and traffic grooming, a CoS-enabled path selection algorithm with traffic grooming function (CPSATG) is proposed in this paper. Simulations are conducted to compare the proposed scheme with methods which have not considered CoS and traffic redundancy. Results show that CPSATG has a much better blocking probability performance and effective resource utilization than the existing methods with almost the same cost of network nodes.