The fuzzy fault tree theory based on T-S model was introduced and applied to the hydraulic system of anchor drill truck.The T-S fault tree of the hydraulic system of the anchor drill truck was constructed.The fuzzy failure probabilities of the hydraulic system of the anchor drill truck were calculated when the fuzzy probability of the bottom event and the fault degree of the bottom event were known.The results show that there is a relationship between the fault fuzzy probability of each system of anchor drill truck; the reliability of the overall system can be improved through the maintenance of the hydraulic pump in daily use; in the calculation,appropriate membership function needs to be selected,which can be improved through test or maintenance data to improve the accuracy of fault diagnosis and analysis.