From the perspective of the influence of normal vibration on friction, considering both normal and tangential vibrations of the vibrating plate, an experimental setup was designed independently to measure the friction at different vibration frequencies. Based on Coulomb’s friction law, a macroscopic dynamic model was established to analyze the mechanism of friction reduction affected by vibration frequencies. The results indicate that the simulation results are generally consistent with the experimental results. When the normal amplitude and average sliding velocity are constant in the presence of both normal and tangential vibration, the greater the vibration frequency, the longer the total time of sticks or the changes of friction direction per unit time will be. Consequently, this leads to more significant friction reduction at the interface and shows that Coulomb's friction law can explain the reason for friction reduction under low-frequency vibration conditions.