Combined with the visual attention mechanism, the influence of contrast factor on visual comfort of stereo image is studied quantitatively through a large number of subjective experiments. First, a stereo salient degree map is derived from stereo disparity map and planar salient map. It is optimized through fuzzy membership degree and mask, and the salient stereoscopic images can be obtained. An eye tracker is used to verify its rationality. Then, a series of subjective experiments are conducted after contrast conversion of left and right views. Finally, the comfortable contrast matching map and difference map are obtained after data screening. The experimental results show that the contrast difference thresholds of left and right view change with different left view contrasts, and the contrast difference should not be too large. The maximum and minimum difference values are 1.97 and -2.40, respectively. The obtained comfortable contrast ranges reflect the comfort of stereo image better, and the correct rate reaches 95%, which provides more reasonable and feasible quantitative standards for the making of stereo contents.