The use of base-isolation technology to resist earthquake damage has attracted much attention since its appearance. Many researchers at home and abroad have conducted studies focused on base-isolated structures under seismic ground motions. Near-fault pulse-like ground motions comprise a velocity or displacement pulse component and other components. Some research results showed that near-fault pulse-like ground motions can cause severe damage to structures. Seismic responses of base-isolated structures under near-fault ground motions have attracted much attention in recent years. Synthetic ground motions were used as input, then the influence of ground motion parameters and isolation-bearing parameters on base-isolated structural seismic responses were analyzed on the basis of nonlinear dynamic time-history analysis. First, a nonlinear motion equation of a base-isolated structure was established. Second, the structural nonlinear dynamic responses were solved under synthetic pulse-like ground motions by using MATLAB. And last, the effects of the velocity pulse period, the yield force of the isolation bearing, and the stiffness ratio of the isolation bearing on dynamic response of the isolation layer and superstructure were studied. Research results show that the effect of the velocity pulse period on the structural dynamic response was great, and the structural natural period should be distant from the pulse period. The influence of the stiffness ratio on structural response was significant, and it should be taken seriously when choosing isolation bearings. The yield force of the isolation bearing had a great influence on bearing displacement, and when the yield force became greater, the bearing displacement became smaller.