The invention discloses a function and application of a (pro) resin receptor [(pro) resin receptor, (P) RR] inhibitor in nonalcoholic fatty livers and fat diseases. Under the background of C57 mice, (P) RR liver specificity knock-out/know-down mice are used as experimental objects, according to a fat mouse model which is induced through high-fat feed, and it is proved through a result that the size of the liver (P) RR knock-out mice is remarkably small, and the fat tissue in the mouse bodies is remarkably reduced; after the mice are fed with the high-fat feed, the increase amplitude of the weight of the mice is low, fat is not generated, the blood glucose content is low, through results of oil red dyeing, liver lipid measurement and the like, it is explained that the liver function of theliver (pro) resin receptor knock-out mice is remarkably better than that of contrasted fatty mice, the fatty liver lesion of the mice is remarkably improved, the stored lipid is remarkably reduced, and the blood glucose content is lowered. Therefore, (P) RR can be used as a medicine target of screening treatment of type-II diabetes, nonalcoholic fatty livers and fat diseases, and the inhibitor of(P) RR can be applied to preparation of medicine for treating type-II diabetes, nonalcoholic fatty livers and fat diseases.