Abstract: The application provides drugs, expression vectors, and their applications in the treatment of NAFLD and related diseases, pertaining to the technical field of targeted drugs. The drugs include streptavidin or a recombinant expression vector for streptavidin. Streptavidin can bind to acetyl CoA carboxylase 1, alter its subcellular localization within mammalian cells, and ultimately inhibit de novo lipogenesis. Ectopic expression of streptavidin can inhibit lipid accumulation within mammalian cells. Compared with chemical small-molecule drugs, streptavidin, as a protein drug, exhibits relatively lower liver and kidney toxicity. Streptavidin might be a relatively mild inhibitor of acetyl CoA carboxylase, avoiding a severe side effect of hyperlipidemia. Furthermore, streptavidin is very stable, which might be conducive to drug delivery and adaptable to different administration methods.