1. A caching method for a multi-layer video network, wherein the multi-layer video network comprises at least one parent node and multiple child nodes connected to the parent node, comprising: collecting a user request arrival rate of each child node with respect to each content in a content set; and determining an optimal storage policy and an optimal upload bandwidth allocation policy of each child node with respect to each content based on the user request arrival rate, storage capacity and upload bandwidth of each child node, and a size of each content.