The invention relates to an elimination method for microorganisms in transformer oil, and belongs to a treatment method of the transformer oil. The elimination method comprises the following steps: carrying out high-pressure and high-temperature dry heat treatment at the pressure of 118-122 kPa, and heating to be 124-128 DEG C for 28-32 min; adding a sterile mixed type adsorbent after the transformer oil is cooled to be 50-60 DEG C, uniformly mixing and stirring for 1-2 h, filtering the transformer oil mixed with the adsorbent by using a pressure type oil filter, then introducing a vacuum oil filter, atomizing the oil by utilizing the introduced vacuum oil filter, separating and removing water due to the boiling point difference of water and oil under a vacuum state, and finally condensing and recycling oil drops repeatedly. The elimination method has the advantage that the microorganisms in the transformer oil are efficiently eliminated, and colloidal substances formed by other impurities in the oil can also be eliminated, so that the purposes of reducing oil medium loss and recovering oil quality are achieved, the economic loss caused by the fact that new oil is replaced by poor treatment is saved.