Abstract:In the study the extruding technic had been used to increase the content of soluble dietary fiber. Based on the single factor experiments， the orthogonal experiment was used to confirm the optimization of extrusion conditions， and compared the carrots residue's chemical and physical properties before and after extrusion. The result which the optimum condition of extrusion spray technic to improve the soluble dietary fiber （SDF） in carrot residue was as follows： die hole diameter 4 mm， temperature 180 ℃， screw speed 175 r/min. Made the SDF content increased to 27.3 % from 16.8 % in raw materials， and other basic nutrients contents didn't change. As well， physical experiments showed that the water holding capacity， oil holding capacity， water -solubility， and swelling properties of extrusion carrot residue were improved. The scanning electron microscopy （SEM） figure indicated that carrot residue appeared thermal degradation and its structure became porous after extrusion. Differential scanning calorimetry （DSC） showed that extruded carrot residue remained structural stability between 25 ℃-200 ℃. Infrared spectrum scanning showed that extruded carrot residue fiber chemical structure had not changed.