The invention relates to the technical field of power equipment monitoring and provides a substation transformer audio monitoring device. The substation transformer audio monitoring device comprises a monitoring module and a monitoring server. The monitoring module is fixedly mounted on a transformer of a substation. The monitoring module comprises a sound sensor, a frequency converter, a controller, a memory and a communication processing chip. The device is reasonable and compact in structure and convenient to use, and can judge a plurality of different fault states of the substation transformer based on audio signals emitted by the transformer, thereby improving integration level of the monitoring system, reducing patrol frequency of work personnel and reducing cost. Besides, the controller and the memory can prejudge the audio signals and directly send the prejudged signals to a background instead of sending the audio signals to the background and then, carrying out signal processing and judgment; and the background can directly assign corresponding maintenance personnel according to the prejudged signals, thereby improving work efficiency.