Abstract: The similarities and differences between JWL model and Landau model and those between strain strength distribution model and strain softening model are discussed, and the JWL model and strain strength distribution model are adopted and introduced in CDEM source program. By using the improved CDEM program, the failure process of rock under explosive loading is studied, and the dimensionless radii of crushed and damage zones and the total fracture degree are mainly analyzed. According to the study, some useful results are obtained: (1) The maximum strain strength is the key parameter to control the failure process. With the increase of the maximum strain strength, from 0.5% to 5%, the dimensionless radius of crushed zone decreases from 37 to 4, the dimensionless radius of damage zone decreases from 45 to 12, and the total fracture degree of rock decreases from 55% to 5%. (2) Under the same strain strength, the occurrence of shear failure is easier than that of tensile failure. The dimensionless radius of failure zone due to shear failure is 2-5 larger than that due to tensile failure, and the total fracture degree is 3% larger. (3) If the tensile failure is the main factor, the fractures in damage zone will propagate along the radial direction straightly. If the shear failure is dominant, the curved fractures will happen.