The utility model relates to a data transmission device of transformer substation, including drive circuit, opto electronic device and close the light ware, drive circuit is connected with the electrical equipment's of transformer substation treater and opto electronic device respectively, and opto electronic device still is bare the ware and is connected with closing. The light signal of different wavelength is launched to the treater through drive circuit drive opto electronic device to with the smooth signal transmission of different wavelength to closing the light ware, close the light ware and merge the light signal of different wavelength, obtain to merge the light signal, and will merge the light signal and transmit. Have in electrical equipment multiple different grade type wait that it need convey to send the message time, can drive the light signal that opto electronic device sent different wavelength through drive circuit, is merged the light signal to the light signal of different wavelength and is transmitted through an optic fibre to the transmission of the message of multiple different grade type in can realizing between the electrical equipment through an optic fibre need not separately to transmit every kind of message respectively through the multifiber, thus reducible optic fibre quantity.