The invention relates to an experimental device of relationship between generation of dam supersaturated total dissolved gas and bubble size, which comprises a water column, a total dissolved gas measurer, an air compressor, flow meters and valves, and also comprises a rotating bearing, an air cavity and screens. The first valve, the second valve and the third valve are arranged at the bottom outside the water column in parallel and are respectively connected with the first flow meter, the second flow meter and the third flow meter which are connected with the air compressor; the air cavity is arranged at the bottom inside the water column and is connected with the three valves at the bottom outside the water column; the first screen is arranged on the air cavity, the second screen is arranged on the first screen in parallel and is connected with the rotating bearing; and a probe of the total dissolved gas measurer is inserted into the water column when in measurement. The invention can realize that factors of bubble size, water pressure, gas mixing amount, bubble pressure bearing time, water depth and the like influencing the generation of the supersaturated total dissolved gas are controlled; and the quantitative analysis of the relationship of the bubble size and TDG (Total Dissolved Gas) supersaturating in the supersaturated total dissolved gas can be carried out by using the device.