The invention discloses a power transformer partial discharge positioning method by means of time reversal. The method comprises the steps of performing time reversal processing on measured power transformer partial discharge data, then, determining the power transformer partial discharge ultrasonic arrival direction according to time reversal ultrasonic signals, and then, determining the power transformer partial discharge position by searching in the partial discharge ultrasonic arrival direction. Accordingly, the search range can be greatly reduced, the time needed by searching the power transformer partial discharge position is greatly shortened, and the measuring efficiency and positioning precision of the power transformer partial discharge position can be improved.