Network file transfer method and system

The invention discloses a network file transmission method and system. The method comprises the steps: a client end sends a network file request message carrying a first network file identification, wherein the network file request message is used for requesting to obtain current contents of a network file to a server by a client end, the first network file identification is used for indicating the obtained contents of the network file of the client end; the client end receives a difference file from the server, wherein the difference file stores a difference value of the current content of the network file and the obtained contents of the network file of the client end; and the client end synthesizes the difference file and the obtained contents of the current file of the client end to obtain the current contents of the network file. According to the invention, transmission flow is reduced, and transmission time is shortened.