The compression modulus E_s? is a fundamental parameter for evaluating soil compressibility and calculating foundation settlement. Enhancing the reliability of the test results of the compression modulus of foundation soil is of great significance for accurately classifying soil types and dividing soil layers. This article conducted in-situ testing on the subgrade soil of a certain expressway in Hunan province using a pore pressure static cone penetration test (CPTU), and took undisturbed soil samples at different depths to measure their compressive modulus indoors. Based on CPTU test data and compression modulus test results, soil layers were divided and the applicability of multiple existing empirical formulas for calculating soil compression modulus based on CPTU collected data was evaluated. Furthermore, a correlation between compression modulus and CPTU cone tip resistance was established. The results show that using CPTU in-situ detection data for soil layer division is relatively reliable. The calculation formula for soil compression modulus based on CPTU in-situ test data established in this paper has high accuracy and can be used as a reference for engineering applications.