File downloading method, file downloading device and file downloading system

The invention discloses a file downloading method, a file downloading device and a file downloading system, which are applied to a transmitting system under a client-proxy-server mode. A monitoring client is arranged in a server. The method comprises the following steps that: a proxy receives a file downloading request from the client and sends a file content checking request to the monitoring client; the monitoring client checks the content of a file to be downloaded and returns a check result to the proxy; and the proxy performs subsequent data forwarding according to the check result. Consequently, the proxy needs not to check the file content and cache a large amount of data therefore, but is only required to perform specific data forwarding according to the check result of the file content, so requirement on the allocated memory size of proxy equipment is low and no additional memory needs adding to cache the file. Meanwhile, the concurrency performance of the proxy can be improved remarkably and the response delay of the client is shortened.