Abstract: The complex non-linear responses analyzed are of a two-span elastic rotor-bearing system with coupling faults of crack and rub-impact supported on three plain journal bearings.A dynamic model of the rotor-bearing system is established considering the oil film force and the nonlinear friction force.The nonlinear dynamics behaviors that induced by crack,rub-impact and coupling faults are numerically studied.Chaos motion appears within the super-critical speed range in the cracked rotor-bearing system,quasi-periodic motion within the sub-critical speed range in the rub-impact rotor-bearing system.Period-4 motion appears within the super-critical speed range in coupling faults of crack and rub-impact system.The influence on the nonlinear characteristics of the system is not clear when the crack is small.The results may bring up theoretical references for fault diagnoses,dynamic design,and security running to rotor-bearing system.