The bubble formation from a submerged orifice in a liquid pool is an important phenomenon in the filtration and discharge process of gas in the containment. During filtration, the size of bubbles from the submerged orifice directly affects the rising speed and the gas-liquid contact area of the bubbles, and thus is one of the important parameters affecting the filter filtration efficiency. As the filtration proceeds, the aerosol content in the liquid pool, among others, may affect the bubble size. This paper conducts a visual experiment to study the bubble formation from a submerged orifice in a liquid pool containing BaSO4 or TiO2 aerosol and to observe and analyze the change law of the size of bubble from the submerged orifice, thus to gain the mechanism of the effect of aerosol on size of bubble from the submerged orifice. The results show that high temperature liquid pool and TiO2 can increase the bubble size, but adding BaSO4 has no obvious effect. Also, the experiment shows the presence of “small air cavity” on the top of the bubbles formed, and the changes of surface tension and “small air cavity” form the main change mechanism of bubble size.