In the traditional classification of the soil stratums, geological engineers mostly classify the soil stratums according to their experience. However, it is very probable that these classification results are subjective, random and uncertain. There is a significant regional difference, so different people may have different results for the same soil stratums classification. Therefore, the concept of fuzzy cluster is introduced in this paper, which makes the physics-mechanical indexes of the soil as the basic parameters, and the soil stratums are classified through mathematical analysis. In order to ensure that classification results are reasonable and effective, the cluster validity index is applied to test results. Through engineering examples analysis, the present classification method is practicable in geotechnical stratums division.