The invention relates to an air bubble detection method for an air tightness test. The method comprises the following steps: a camera carries out shooting; inter-frame difference method comparison is carried out on an image; clustering analysis is carried out on coordinate points of a frame difference pixel; a frame difference image NewDiffImg is obtained; analysis in a centroid distance variance method is carried out; radius and roundness error values are compared; the leakage rate is obtained and the like. Compared with the prior art, the method has the following beneficial effects that a computer vision technology is used for detecting air bubbles in a pressure container air tightness test, the camera is directly used for acquiring the image, the operation is simple, the cost is greatly reduced in comparison with the fact that an expensive device such as a fiber probe and an electron probe acquires physical parameters, impurities whose shapes are similar to air bubbles can be well eliminated, the image is shot from the water surface of a detection pool, the air leakage position can be positioned, and accuracy of the detection result can be improved.