The invention relates to the technical field of ore washing, in particular to a method for reducing wear of a tail shaft and an underwater bearing bush of a trough type ore washer. The method comprises steps as follows: shaft sealing water is provided by a high-position water tank through a main water supply pipe and a shaft sealing water pipe, ore washing water is provided by a return water tankfor the ore washer, and supplementary water of the return water tank is provided by the high-position water tank. The method further comprises the steps as follows: improvement of a water supply network: a booster pump and a filter net are arranged between the high-position water tank and the main water supply pipe, and a solenoid valve is arranged on each branch water supply pipe; improvement ofthe shaft sealing water pipe: the shaft sealing water pipe adopts a straight pipe and is equipped with a blow-off valve; improvement of the supplementary water of the return water tank: the supply quantity and the supply manner of the supplementary water are controlled by a controller; cleaning measures: the high-position water tank is cleaned periodically, and shutdown cleaning is performed. Withthe method, the wear of the tail shaft and the underwater bearing bush of the ore washer can be effectively reduced, the ore washing yield can be increased, the repair cost of the tail shaft can be reduced, and the loss cost of the underwater bearing bush can be reduced.