Based on the recent reports from domestic and foreign researches, this study elaberated plant food by-products processed by solid-state biotransformation for the enzyme production efficiency and its potential applications. In addition, this study also reviewed solid-state biotransformation on the influence of major biological compounds (e.g., phenolics, flavonoids, polysaccharides etc.) and bio-activities of plant food by-products, and prospected its direction for future development.