With the advance of science and technology, wireless networks are becoming a significant part of today's access networks. Ad hoc networks are wireless mobile networks without an infrastructure. Recently more and more multimedia services are applied to ad hoc networks. Because of the problem of the mobility, it always makes the interruption of video packets transmission, which causes the worse quality of videos. In order to solve above problem, we propose a novel peer to peer (p2p) caching system, using radius-based binary search algorithm and mobile management. In order to transmit video packages via ad hoc network, we adopt layered scalable video coding. Video is encoded into three layers by layered scalable video coding. By radius-based binary search algorithm and mobile management, we can increase the hit radio of the p2p catching and shorten the cache distance.