This study focused on the improvement of nutritional value of compound protein feed (CPF) through solid state fermentation. CPF was fermented with C.utilis, B.subtilis and Lactobacillus for 3 days, then was dried into fermented compound protein feed (FCPF). Digestion and metabolism experiments of soybean meal (SBM), CPF and FCPF were conducted on the basis of analysis of nutrients and amino acids content. Twenty-four Duroc×Landrance×Yorkshire growing pigs with body weight of (24-36±1-78) kg were randomly allocated into 4 groups with 6 replicates in each group and 1 pig in each replicate. Pigs in 4 groups were fed N-free diet and semi-purified diets with CPF, FCPF and SBM as only protein source, respectively. The experiment lasted for 4 days for adaptation, and 4 days for sampling. The digestibility and availability of protein and energy, and ileal digestibility of amino acids on growing pigs were determined by N-free diet method. The results showed that, solid state fermentation could significantly improve the crude protein, true protein, calcium and total phosphorus contents of FCPF (P＜0.01); content of amino acids except arginine were improved. Compared with CPF, digestibility and availability of protein and digestibility of energy (P＜0.01), apparent digestibility of amino acids (P＜0.05 or P＜0.01) and true digestibility of amino acids (except Gly) (P＜0.05 or P＜0.01) were significantly improved. Most nutritive property were closed to or better than SBM. In conclusion, solid state fermentation could significantly improve the nutritive property and nutrient digestibility and availability of FCPF on 20-50 kg growing pigs.