As the fault of Nose Wheel Steering（NWS）system is of concealment under the existing planned maintenance system，the potential fault early warning method of NWS is studied by mining the post flight Quick Access Recorder（QAR）data. Firstly，on the basis of analyzing the failure mode of NWS，the monitoring QAR parameters relating to the NWS failure are selected and handled. Secondly，based on the normal and faulty cases of NWS，combined with the operational principle of NWS，the Pearson correlation coefficient analysis method is used to determine the potential failure characteristics of the low correlation between the command value and actual value，so as to realize the detection of potential failure. Finally，the actual case of NWS is used to verify the effectiveness of the potential fault warning method based on QAR data，which provides a reference for the formulation of condition based on maintenance strategy of NWS.