Friction is a phenomenon caused by relative motion, which can be used to absorb vibrational energy. The influence of friction on vibration responses of structures is complex due to the complicacy and nonlinear of the friction itself. In this paper, a 3-DOF spring-damper model with/without friction force was studied to expose how the friction governed the vibratory responses. Several popular friction models were reviewed and LuGre Model was used in this paper. The vibration properties under sine excitation and random were simulated by the Matlab Simulink Software. The results showed that friction absorbed vibration well and vibration damping was rapid. The characteristics of friction influence resulted from comprehensive functions of all factors, such as types of excitation, excitation amplitude and frequency and the location of friction.