The invention relates to an optical transformer fault diagnosis device. The device includes an optical fiber transceiver, a core module, an upper computer interface and a wireless module; the optical fiber transceiver is used for receiving optical signal data of an optical transformer to be diagnosed in real time, converting the optical signal data to corresponding electrical signal data and transmitting the electrical signal data to the core module; the core module is used for receiving configuration information from an upper computer through the upper computer interface and configuring itself according to the configuration information so as to satisfy the communication protocol of the optical transformer to be diagnosed; the core module is also used for analyzing the electrical signal data received from the optical fiber transceiver so as to obtain the status information and fault diagnosis result information of the optical transformer to be diagnosed; and the wireless module is used for transmitting obtained status information and fault diagnosis result information of the optical transformer to be diagnosed to a remote terminal. The device is easy to carry, and can be connected into an optical transformer and complete the fault diagnosis of the transformer.