Based on fluid dynamics, a simulation model of transformer oil containing bubbles streamer discharge under the action of impulse voltage is established. The variation laws of electric field intensity and space charge density of transformer oil containing bubbles are studied by changing the position, size and number of bubbles. The simulation results show that when the breakdown voltage reaches a certain value, an electric field gradient is formed inside the bubble due to the accumulation of gas inside the bubble, resulting in an internal discharge phenomenon. The closer the bubble is to the high-voltage electrode the faster it is broken down, and the discharge proceeds in a relatively shorter time. The larger the size of the bubble, the slower the transformer oil streamer discharge. And the more the number of bubbles , the more intense the electric field during the streamer discharge, the longer the discharge lasts, and the greater the damage caused to the transformer.