The invention discloses an experimental device for release accelerating research of oversaturated gas in under-dam watercourses. The experimental device comprises a circulating water pool, a variable-frequency water pump, a high-pressure reactor, a slope-variable thermostatic water bath and a grit chamber which are in sequence connection. A water outlet of the grit chamber is connected with a water inlet of the circulating water pool to form water circulation. The high-pressure reactor is connected with an oxygen supply box inputting oxygen therefor and provided with a gas regulating valve, a safety gas valve, a gas pressure gauge and a total dissolved gas determinator. A silt input box is arranged at the top of two side walls of the thermostatic water bath. A turbulence speeding device, a node model, a front total dissolved gas determinator, a rear total dissolved gas determinator, a front three-dimensional ADV (acoustic Doppler velocimetry) instrument and a rear three-dimensional ADV instrument are arranged in the thermostatic water bath. The experimental device is simple in structure, convenient to use and capable of satisfying mechanism research of oversaturated gas in under-dam watercourses in terms of water turbulence, silt, different watercourse node boundaries, water temperature and the like.