The method of ion chromatographic analysis was used to analyze major salt induced diseases of wall paintings in Moni Temple of Longxing Temple, and the non-destructive testing methods included electrical resistivity tomography, microwave moisture measurement, thermal infrared imaging and temperature and humidity monitor were applied to survey the source water vapor source. The results showed as follows: NaCl is head fact induced disease; there are latent areaways in walls and buddha stage; at the same time, the temperature difference between the lesion area and the surrounding murals accelerates the velocity of water vapor migration; the main water vapor source is water vapor in the air of Moni Temple and atmospheric rainfall.