This study was conducted to investigate the effect of sequential and direct detergent methods on the monosaccharide composition of acid detergent residues in three fibrous feedstuffs (lignified, highly digestible and highly pectic). The result indicated that the contents of ADF and cellulose determined by the sequential detergent method were lower than those determined by the direct detergent method (P<0.05). Compared with the direct detergent method, the sequential detergent method had lower content of each hemicellulosic monosaccharide contaminations, including xylose, mannose, arabinose and galactose (P<0.05). Based on the present data, the sequential detergent method should be recommended in regular laboratory analysis of fibrous feedstuffs for effective removing contaminated hemicellulose sugar units.