Dynamic random-dot stereograms which can eliminate the effects caused by psychological clues of stereo vision were used to study the depth motion characteristics of stereo vision. The effects on Stereo Visual Comfort(SVC) of the depth motion characteristics including motion positions, motion directions and motion velocities were analyzed by subject experiments and a prediction model of visual comfort and motion velocity during depth motion was built. The results show that depth motion induced perspective and depth motion make different visual comforts under crossed disparity(before the screen) or uncrossed disparity(after the screen) in dynamic random dot stereograms. The Pearson Correlation Coefficient(PCC) of three types of depth motion achieves 0.956, 0.972, 0.977, respectively, which indicates that the prediction model can more accurately predict the SVC.