A local discharge ultrasonic positioning method based on a flexible array sensor; the method comprises the following steps: using the flexible array sensor to collect supersonic wave signals on the outer surface of detected electric equipment; using Euler transformation to transform a radiation direction in a local coordinate system into a radiation direction in a global coordinate system; using a dimension reduction MUSIC algorithm to solve estimation values of a local discharge source azimuth and a pitch angle; determining a connecting line between the sensor and the local discharge source according to the estimation values and known sensor coordinates; finally solving crossing points of the connecting line between sensor in many measuring positions and the local discharge source, thus obtaining the local discharge source accurate position. The method uses the flexible array sensor to collect the supersonic wave signals in the detected electric equipment, thus ensuring each array element to excellently attach to the electric equipment surface, well solving the accurate detection problems of the electric equipment local discharge source in a random shape, and providing effective paths for analyzing and determining the equipment internal fault severe level.