Visual perceptual degradation is usually introduced during 3D mesh simplification. Some geometric metrics without considering human visual perception and perceptual metrics based on subjective test have been proposed. A new Global Perceptual Structural Degradation metric (GPSD) based on mesh saliency and information theory to evaluate the visual perceptual degradation is proposed in this letter. It can also provide the function of multi-scale evaluation of visual degradation effectively. The accuracy and validity of the proposed metric have been demonstrated through subjective experiment.