Two simulation models are established by Simulink to verify and analyze the impact of aperture jitter on SNR in ADC in software radio. The first simulats the effect of the sampling ADC aperture jitter using the jitter of input signals, and the second simulats the ADC sampling clock jitter more accurately by adding the Gaussian noises to the clock source. The simulation curves of these two models are consistent with the theoreticalones, which verifies that the models are correct, especially for the second. It resolves two key issues, the generation of the sampling jitter pulses and the signal synchronization in parameter calculation, and more truly and accurately curves are obtained, and it provides a more reliable basis for an indepth study of measurement, analysis and control of highspeed and high precision ADCs’ aperture jitter, which is helpful in the design of the system.