The present invention provides a self-absorption type electric leakage monitoring device and a monitoring method. The self-absorption type electric leakage monitoring device comprises a fixing bench and an acquisition module, a filtering module and a processing module which are installed based on the fixing bench and are connected with a power supply module separately. The acquisition module comprises a high frequency current sensor and a conduction antenna connected with the high frequency current sensor, and the processing module comprises a controller and a connected digital signal processor, and the fixing bench is made of a magnetic material and absorbs the outer surface of an extra-high voltage transformer shell. According to the present invention, by real-timely monitoring the electric leakage of an extra-high voltage transformer, the problems that the current extra-high voltage transformer electric leakage detection means is single, and the precision is low, are solved, and when an electric leakage phenomenon occurs, an alarm signal can be sent out timely, and the emergency measures are adopted automatically to remind the workers to inspect and maintain, thereby preventing the extra-high voltage transformer from burning out.