Information transmission method, proxy server and service system in network

The embodiment of the invention discloses an information transmission method, a proxy server and a service system in network. The information transmission method comprises the following steps: the proxy server receives a download request message for requesting to download files sent by a client-side, judges whether the files requested by the client-side are stored locally; if so, the locally stored files requested by the client-side are sent to the client-side; if not, the files requested by the client-side are downloaded from an application server of a network side and are sent to the client-side after being stored. The embodiment of the invention also provides a corresponding proxy server and a service system. The technical scheme of the embodiment of the invention can relieve network congestion.