Unlike traditional routing schemes that route all traffic along a single path, multipath routing strategies split the traffic among several paths in order to ease congestion. It has been widely recognized that multipath routing can be fundamentally more efficient than the traditional approach of routing along single paths. According to the characteristics of ant colony algorithm and the ideal of multipath routing. This paper proposes a QoS multipath routing on ACO Algorithm. ACO was improved in three aspects. As a ant selects the next hop, the utilization ratio of router's buffer queue is added into the criterion of selection, introducing the utilization ratio of link to update the global pheromone, selecting multiple paths to transfer data. Simulation experiments show the algorithm can achieve network loading balance, reduce the likelihood of congestion, and impove the utilization of network resources.