Abstract: A kind of automatic separator of fly larvae based on negative phototaxis was designed，which could realize automatic feeding，layer scraping of feces and automatic drop of flies.The separator has high separation rate，low energy consumption and simple structure，so as to solve technical bottleneck in industrialization of biological transformation of fly maggot in livestock and poultry，and reduce cost of maggot dung separation. Social，economic and ecological benefits were significant，while promoting sustainable development of livestock and poultry and aquaculture，reducing pollution of agricultural and rural areas，was of great practical significance for promotion and development of modern ecological recycling agriculture.