Abstract: According to the recount and analysis about the principal of effective stress, strength criterion, settlement calculation, constitutive model, unsaturated soil and calculation parameters in engineering practice of soils, it is drawn that the pragmatism is a characteristic and effective work method in the subject of soil mechanics. The soil is a very complex kind of material, and soil mechanics is a practical subject. Therefore, the researches on the soils have to be based on engineering application because of the pragmatism characteristic of soil mechanics. The pragmatism and empiricism are often interlinked with each other, and the concept and theory in soil mechanics are not allowed to be overlooked.