Disparity is one of the main factors which affect the visual comfort of stereo content. Combined with the visual attention mechanism, the influence of disparity factor on visual comfort of three-dimensional (3D) image is studied through a large number of subjective experiments and a quantitative range is obtained. First, the salient stereo image is obtained through a stereo salient region extraction algorithm, and an eye tracker is used to verify its rationality. Then, the pixel shifting method is used for disparity conversion on the salient stereo image. A large number of subjective experiments are carried out with the converted images. Finally, the comfort disparity range is obtained after process of the experimental data. The experimental results show that the human visual system responds very differently to horizontal disparity and vertical disparity, and the comfortable range of horizontal disparity is (-0.379°,0.644°), while the comfortable range of vertical disparity is (-0.10°,0.11°). The correct rate of verification experiment is over 90%, which indicates the obtained comfortable disparity ranges reflect the comfort of stereo image well, and can provide a quantitative standard for the making of 3D contents.