Abstract: Based on a lot of dynamic triaxial tests, some dynamic characteristics on intact loess under the train vibration load are studies. The test results showed that when the intact loess was under certain dynamic stress, strain increased with the increase of the number of vibration, and decreased with the decrease of consolidation stress. The relation between stress and strain can be fitted with hyperbolic model under certain conditions. When dynamic stress was smaller, strain could be fitted linearly with dynamic stress. But with dynamic stress increased more than a certain threshold, strain of intact loess would be increased dramatically. And the growth rate of strain increased with the increase of the number of vibration. Under the certain number of vibration, strain of loess decreased with the increase of vibration frequency. And the frequency was smaller, the turning point appeared earlier. Dynamic modulus of intact loess decreased with the increase of dynamic strain and the trend was basically similar when K_c is equal to 1. Dynamic damping ratio did not have obvious increasing trend but had scatter distribution when the strain increased, its discrete values were in the range of 0.10 to 0.30.