Abstract: Solid-state fermentation of the waste produced in orange processing to produce feed was studied.A strain of Penicillium sp.which could produce high cellulase was screened.Its optional soild medium was:citrus peel∶bean cake∶wheat branr=15∶1∶1,solid substance∶water=2∶1,(NH₄)₂CO₃3%,pH 4.5.And the optional condition for enzyme production was:culture temperature 30 ℃ and culture time about 84 h.This provides a good way to utilize the waste produced in orange processing to produce useful matter.