The invention belongs to the technical field of nuclear power plant operation and maintenance, and particularly relates to an experimental device and method for detecting the rubber permeability. A left chamber and a right chamber of the device are connected through a butt clamp flange, and to-be-detected rubber is clamped in the middle of the butt clamp flange; the left chamber is connected witha helium mass spectrometer through a detection pipeline, and the right chamber is connected with a helium bottle through an inflation pipeline; and the right chamber is also connected with a positivepressure gauge and a negative pressure gauge for monitoring the gas pressure in the right chamber. During use, a positive pressure helium leak detection method and/or a negative pressure helium leak detection method are/is adopted, the right chamber is vacuumized while the right chamber is filled with high-pressure helium gas or the left chamber is filled with low-pressure helium gas, and the helium content of the left chamber is detected through the helium mass spectrometer, so that the leak rate of the to-be-detected rubber is obtained. The experimental device and method have the beneficialeffects that the characteristics of high permeability, easy diffusion, high diffusion speed and the like of the helium gas are utilized, technical means of vacuumizing, helium mass spectrometer leak detection and the like are adopted, and the experimental device and method are suitable for detecting the permeability of various rubber materials, so that experimental results are obtained more quickly and effectively.