Immanent factors and change process in land degradation through soil degradation process is reflected, the main types of soil degradation are soil erosion and land desertification. This article take soil erosion as main degenerated form research land degradation intrinsic major effect factor. But soil erosion's major indexes are soil anti-scouring, soil anti-scouring macroscopic representation is soil anti-shear strength. How in situ testing, the quantitative reflection soil degradation's intrinsic factor is the soil degradation new problem. To solve this problem, the research and development has been able to reflect the soil degradation major effect factor the apparatus of mensurated soil anti-shear strength. This instrument has functions and so on man-machine interface, data storage, serial port communication, and uses the least square method analysis and digital filtering in order to the data analysis, the curve fitting. After and the traditional experiment's result contrast, has confirmed instrument's feasibility, the usability and the accuracy. Research on prevention of soil degradation in the main factors providing new ideas and concepts; can be a new index for monitoring soil degradation; and monitoring of soil degradation, provides a new technological means.