The work aims to study the influence of salt/water ratios on the appearance and developing rate of mural disruption in a nondestructive testing (NDT) method. Disrupted mural samples of nine salt/water ratios were made and disposed in the temperature and humidity chamber for wetting-drying cycle test. Digital photos of the mural samples after each cycle period were analyzed by virtue of Matlab software and self-programming software, so as to obtain 3D distribution diagrams and quantized data at sample surface height. During the studied time range, the sample with salt/water ratio of 1:10 was subject to no obvious disruption damage. The samples with salt/water ratios of 2:10 and 3:10 were subject to the disruption damage similar to that in Mogao Grottoes. The samples with salt/water ratios of 4:10, 5:10, 6:10, 9:10, 11:10 and 13:10 were subject to cracking and flaking in pigment layer, then falling off of base layer and pigment layer. Developing rate of the mural disruption was time-phased. The higher the salt/water ratio was, the more risk of mural disruption damage and developing rate would be. Combining the damage developing morphology with Matlab software is a nondestructive and quantifiable method of obtaining the development model and rate of mural disruption.