The invention discloses a file transfer method and a file transfer device for an electric power system. The method comprises the following steps of: acquiring a first hash value of a first file, wherein the first file is the one needed to be transferred, and the first file comprises a plurality of unit character strings; judging whether a preset database contains a second hash value of which the value is identical to the first hash value; if the preset database contains the second hash value of which the value is identical to the first hash value, transferring a third file comprising the first hash value to a target terminal; if the preset database does not contain the second hash value of which the value is identical to the first hash value, respectively reading compressed codes corresponding to each unit character string in the first file from a compressed code table; and transferring the third file comprising the compressed codes corresponding to each unit character string to the target terminal. With the method and the device provided by the invention, the technical problem of relatively high cost and relatively low safety of data transfer through a mobile terminal in the electric power system is solved.