Abstract: The amount of geologic drilling railway is huge and the management is of vulnerability, which results in many fake SPT (Standard Penetration Tests) and affects the geologists to judge on the formation, and leads to serious consequences. To improve the quality of engineering geological investigation, the investigation of Chang-Yi-Chang inter-city railway is taken for engineering background, and the PDCA model management methods are used to control the process of SPT. The plastic states corresponding to SPT blow counts with the liquidity index of soils are compared and the real ratio is about 79.5%. The method is available in reference for related engineering.