Modelica-based object-orient method is proved to be rapid,accurate and easy to modify,which is suitable for prototype modeling and simulation of rotor system,whose parameters need to be modified frequently.Classical non-object-orient method appears to be inefficient because the code is difficult to modify and reuse.An adequate library for object-orient modeling of rotor system with multi-faults is established,a comparison with non-object-orient method on Jeffcott rotor system and a case study on turbo expander with multi-faults are implemented.The relative tolerance between object-orient method and non-object-orient is less than 0.03%,which proves that these two methods are as accurate as each other.Object-orient modeling and simulation is implemented on turbo expander with crack,rub-impact,pedestal looseness and multi-faults simultaneously.It can be conclude from the case study that when acting on compress side of turbo expander separately,expand wheel is not influenced greatly by crack fault,the existence of rub-impact fault forces expand wheel into quasi-periodic motion and the orbit of expand wheel is deformed and enhanced almost 1.5 times due to pedestal looseness.When acting simultaneously,multi-faults cannot be totally decomposed but can be diagnosed from the feature of vibration.Object-orient method can enhance the efficiency of modeling and simulation of rotor system with multi-faults,which provides an efficient method on prototype modeling and simulation. Modelica-based object-orient method is proved to be rapid, accurate and easy to modify, which is suitable for prototype modeling and simulation of rotor system, whose parameters need to be modified frequently. Class non-object-orient method appears to be inefficient because the code is difficult to modify and reuse. An adequate library for object-orient modeling of rotor system with multi-faults is established, a comparison with non-object-orient method on Jeffcott rotor system and a case study on turbo expander with multi -faults are implemented. The relative tolerance between object-orient method and non-object-orient is less than 0.03%, which proves that these two methods are as accurate as each other. Object-orient modeling and simulation is implemented on turbo expander with crack, rub-impact, pedestal looseness and multi-faults simultaneously. It can be conclude from the case study that when acting on compress side of turbo expander separately, expand wheel is not affected greatly by cra ck fault, the existence of rub-impact fault forces expand wheel into quasi-periodic motion and the orbit of expand wheel is deformed and enhanced almost 1.5 times due to pedestal looseness. When acting simultaneously, multi-faults can not be totally decomposed but can be diagnosed from the feature of vibration. Object-orient method can enhance the efficiency of modeling and simulation of rotor system with multi-faults, which provides an efficient method on prototype modeling and simulation.