The invention relates to an automatic zero adjustment device for an electric steering engine. The automatic zero adjustment device comprises a controller, a proximity switch, a proximity switch support and an extension clamping device; the controller is respectively connected with the proximity switch and the electric steering engine; the extension clamping device comprises a base and a lengthenedrod body, the base is clamped on an output shaft of the electric steering engine, and the lengthened rod body is fixedly connected with the base; when the output shaft of the electric steering enginerotates and drives the base to rotate and the lengthened rod body reaches a triggering range of the proximity switch, output level of the proximity switch turns over, the controller controls the output shaft of the electric steering engine to stop rotating, and mechanical zero adjustment is completed; and the controller is used for acquiring an output voltage value of a sensor, rotating the sensor and stopping rotation of the sensor when an alarm gives an alarm, thus electrical zero adjustment is completed. By using the proximity switch, the extension clamping device, the controller and the alarm, automatic mechanical zero adjustment of the electric steering engine as well as automatic interpretation and hint when a zero position of the sensor is adjusted into position are realized, and efficient and precise zero adjustment of the electric steering engine is improved.