The invention relates to a metallographic phase corrosion method for a copper conductor of a power transmission and transformation device. Firstly, a sample is taken from the copper conductor of a broken power transmission and transformation device, the sample is ground, and then is polished till no scratches are seen by naked eyes, the sample is soaked into a corroding agent to be corroded with the polished face facing upwards, the corroded sample is obtained and then is taken out, the sample is placed into supplementing liquid to continue to be corroded, and the sample is taken out, cleanedand dried. The corroding agent and the supplementing liquid adopted by the metallographic phase corrosion method for the copper conductor of the power transmission and transformation device are simplein formula, easy to prepare, and low in cost and have a good corroding effect on the copper conductor. The method can reduce influences of scratches and the like on the corroded structure, the crystal boundary display effect of the metallographic phase structure of the copper conductor is made good, and fast and accurate detection on the metallographic phase structure of the copper conductor canbe achieved easily.