Abstract: To investigate the intermittent characteristics of friction-induced squeal, a 3-degree-of-freedom (DOF) model of self-excited vibration was established taking into account the frictional surface roughness. The effects of incline angle of surface roughness on the system stability and transient response were analyzed by using numerical computation. A test rig of pin-on-disc was developed to verify the proposed theoretical results. The numerical and experimental results showed that the system stability was mainly dependent on the modal coupling effect of system itself, and was affected by the friction coefficient and the surface roughness as well. The system was prone to instability and producing squeal noise when the incline angle of surface roughness increased to some value.