In order to eliminate the external disturbance and remove the influence of the uncertainty of the steering system kinematics model,a vehicle kinematics model of parallel parking system is constructed and a third- order li- near extended state observer is designed.The observer takes the external disturbance and the model uncertainty for a total disturbance to observe and compensate without building the accurate mathematical model of controlled ob- jects.Based on this observer,a path- tracking controller is established for parallel parking and its control perfor- mance is verified by a simulation and a real vehicle test.Simulation results show that the proposed path- tracking controller shows a better performance and a stronger ability to resist the external disturbance in comparison with those of the traditional PID controller.The real vehicle test results show that the proposed path- tracking controller can control vehicles to finish parallel parking tasks precisely with a maximum error of only 0.111m.