To reveal the damage evolution mechanism and crack classification evolution law of cemented sand and gravel （CSG） materials from a microscopic perspective， the Geiger time difference positioning method， rising angle-average frequency method， and Gaussian mixture model were employed to identify the crack types of CSG materials. The results show that the failure process of CSG materials can be divided into four stages， initial crack closure， new crack propagation， crack coalescence and peak failure. The three-dimensional positioning of acoustic emission events intuitively reflects the dynamic evolution process from crack initiation， propagation to penetration. Through crack type identification， shear cracks predominate in the early loading stage， and the proportion of tensile cracks increases later. Before failure， the ratio of shear to tensile crack is about 2∶1 at high water-binder ratio， and about 1∶1 at low water-binder ratio.