Cellulosic material was inoculated with Trichoderma album by solid state fermentation and the change of protein, total nitrogen, mineral nitrogen, cellulose and total fiber contents of raw material were measured. It was found that the water holding capacity and bulk density of substrate increased as the fermentation progressed. The optimum C/N ratio for the conidia production was between 4 and 7, and the optimum pH was around 5. The protein enrichment of sugar beet residue were the best at the initial moisture content 76%, initial pH 4.5 and supplement with 1% nitrogen. After 4 days fermentation, the final product contained 22% of protein. From the present state of technological development, the protein enrichment of cellulosic materials by solid state fermentation proved to be valuable.