Based on experiments related to the dynamic characteristics of intact loess in Lanzhou, Gansu Province, in this paper, we investigate the prediction of the seismic subsidence of loess under earthquake load. We analyzed the relationship between shear-wave velocity and the seismic subsidence coefficient for different water-content intervals and the functions was polynomial-fitted. In a similar manner, we analyzed water content and the seismic subsidence coefficient at different shear-wave velocity intervals. By analyzing the relationship between shear-wave velocity and water content, we established a new method for evaluating the characteristics of the seismic subsidence of loess by associating shear-wave velocity with water content. We then used this method to predict the seismic subsidence of loess in the Yongdeng earthquake. The results indicate that the seismic subsidence coefficient increases with increasing water content at certain shear-wave velocity intervals and decreases with increasing shear-wave velocity at certain water-content intervals. We determined the absolute seismic subsidence ability to characterize the potential seismic subsidence ability that remains constant in different external loess conditions, as reflected by the shear-wave velocity. We also determined the absolute seismic subsidence coefficient to be proportional. We found water content to influence the release of the potential seismic subsidence ability. We used a case example to demonstrate the obvious practicality of this method.