Abstract: The accumulated water in the accident oil pool of the transformer occupies the volume of the accident oil pool. The capacity of the accident oil pool to contain the transformer accident oil is reduced, and the volume availability of the accident oil pool is reduced. Once the oil stain in the accumulated water is discharged to the outside with the accumulated water, it will cause environmental pollution. Therefore, this paper analyzes the possible reasons for the low volume availability of transformer accident oil pool. In view of the height difference between the installation height of the drainage device and the bottom surface of the accident oil pool, countermeasures are taken. Improve the volume availability of transformer accident oil pool.