Through dynamic triaxial test, we investigate the effect of clay content on unconfined compressive strength, sensitivity, dynamic residual strain, and residual pore pressure of two mucky silty clays with different clay contents. Result shows that the unconfined compressive peak strength of specimen with high clay content is lower than that of specimen with low clay content; the sensitivity of sample with high clay content is greater than that of sample with low clay content. Dynamic residual strain, dynamic residual pore pressure and difference of dynamic residual strain between reconstituted and undisturbed sample increase as dynamic loading increases. Ratio of reconstituted dynamic residual strain to undisturbed dynamic residual strain also increases with increasing of load, and this value is greater than their sensitivity. The dynamic residual strain of reconstituted sample is greater than that of undisturbed sample under the same load. Also the dynamic residual strain of sample with more clay content is larger than that of the sample with less clay content in the case of similar dynamic stress. We conjecture that cementation and lubrication between clay particles cause different results for samples with different amounts of clay, use power function model to fit the curves of gradually stabilized dynamic residual strain, and develop a empirical formula, incorporating cycle stress ratio and number of cycles, for the dynamic residual strain.