A new optical metrology method for measuring soil landslide displacement is presented in this paper. Under the optical experimental system, the soil micro-displacement field can be measured by obtaining the digital images of the soil specimen under water load and searching the gray value in sub-pixels by digital image surface fitting technology. The results show that through the optical system, this nondestructive testing method can improve the measurement accuracy, and has a very good prospect of application in the study of soil landslide. The experimentation can provide useful data for disaster prevention and mitigation research and actual construction. In addition, if using a CCD with higher resolution and more effective record area, or using synthetic aperture technology to increase effective record area, the accuracy of the experiment are expected to be further enhanced.