Fermentation has been used recently in poultry nutrition due to having great potential. It can improve the nutritional composition of feedstuffs, eliminate antinutritional components, enrich with enzymes, phenolic compounds and coloring agents. Fermented feedstuffs can increase performance, feed utilization, digestibility, immunity, antioxidant capacity, intestinal microflora in poultry. Improvements of feedstuffs by fermentation and effects of fermented feedstuffs on poultry are summarized in this study.