The invention discloses a local discharging detection method of an insulating draw bar based on electric field calculation and X-ray excitation. The method comprises the following steps: firstly, applying 1.7-time rated voltage to two ends of a to-be-detected insulating draw bar for one minute, then reducing the voltage to 1.3-time phase voltage, and detecting the local discharging; determining that the insulating draw bar is unqualified if the local discharging is detected; maintaining the voltage if no local discharging is detected, and performing X-ray scanning on the insulating draw bar from a grounding end of the insulating draw bar from bottom to top by virtue of an X-ray generator; and detecting the local discharging when the X-ray scanning is performed on one position, wherein if the local discharging disappears when the X-ray leaves the position, the insulating bar has a defect on the position, and if no local discharging is detected in the whole process, the insulating draw bar is qualified. Different positions of the insulating draw bar are irradiated by X rays with reasonable intensity, so that the problem that the defect on the position with a low electric field cannot be detected due to non-uniformity of the distribution of the electric field can be solved.