IMS-based streaming media service always provides live or on-demand content services for customers. However, the centralized service model does not utilize resources fully but leads to concentrated data flow, which will refuse to provide services for more terminals or even affect the service availability for the failure of the media server. In this paper, an IMS-based overlay network content distribution mechanism to support multipath transmission is proposed. Through the introduction of the overlay network on IMS resource sharing and distribution can be achieved. It also improves the network resource utilization, reduces the load of the central media server. The experiments show that IMS-based overlay network content distribution mechanism has a significant advantage compared with the traditional media server content distribution mechanism.