Abstract: The development of soil mechanics can be divided into four stages based on the deformation characteristics. The first stage is mainly to study the one-dimensional compression deformation of soils, which is marked by the e-p curve of the compression tests. Studying the three-dimensional compression deformation of soils is the second stage, which is marked by the critical state surface of Roscoe, and the three-dimensional surface of e-p-q is established. The Duncan-Chang constitutive model is the symbol of the third stage. It is characterized by the compactness and shear softness of soils, more intuitively focusing on the study of the shear deformation of soils. Moreover, the fourth stage should take the field in-situ soils as the research object, use in-situ testing technology as the main method, master the mechanical properties of in-situ soils, develop in-situ soil mechanics, and better serve the engineering practice. The fourth stage should be a worthwhile direction in the future.