Took extruded wheat bran (the mixture of crude bran, fine bran,wheat germ and wheat shorts) as raw material, the effects of sieving fineness (44.15～198.48 μm) on the physicochemical properties of extruded wheat bran and processing quality of whole-wheat flour were investigated. Results showed that with sieve mesh being increased, particle size distribution in extruded wheat bran became narrow; sieving fineness had great influence on the content of pentosan and ferulic acid, while a little influence on holding water capacity and swelling property of extruded wheat bran, and pasting properties and farinograph properties of whole-wheat flour; The uniformity can be obtained for wheat bran products by being extruded.