The rock foundation of inland ports experiences different degrees of dry-wet cycles，and the bearing performance of the foundation decreases and deteriorates. The number of dry-wet cycles and confining pressure are taken as the working conditions for the conventional triaxial compression test of siltstone. The micro-element strength of siltstone is assumed to obey the improved Harris probability distribution，and then the damage variable is defined. The M-C strength criterion is selected to build a new statistical damage model that can reflect the dry-wet cycle in combination with the logarithmic attenuation law of the elastic modulus and internal friction angle in the test results. The parameter analysis method is given，and the damage development curve is obtained. After that，the new model is used to identify the test curves of siltstone and argillaceous dolomite and sandstone in the literature，and simulations are performed for comparisons. The results show that the elastic modulus，cohesion，and internal friction angle of siltstone decrease gradually with the increase in the number of dry-wet cycles. When the number of cycles reaches 16，the attenuation curve tends to be stable，and the attenuation law can be expressed by the logarithmic function. The dry-wet cycle promotes the attenuation and deterioration of the mechanical properties of rock，and the macroscopic performance is represented by the reduction in peak stress. The feasibility of the new model is verified.