Abstract: Physicochemical and functional characteristics of modified citrus fiber by different method such as ball milling, high-pressure homogenization, ball milling-cellulase, and high-pressure homogenization-cellulase were investigated in this paper. The size of modified citrus fiber was reduced, of which high-pressure homogenization combined with enzyme treatment resulted in a significant reduction in the volume mean diameter from 103.67 μm to 63.23 μm and the area mean diameter from 50.29 μm to 22.40 μm, making it the most effective method for reducing fiber size among the various methods. Infrared spectroscopy and X-ray diffraction studies had shown that the crystallinity of citrus fibers treated with high-pressure homogenization and high-pressure homogenization combined with cellulase treatment decreased, but the main functional groups remained unchanged. The effect of high-pressure homogenization and ball milling treatment on opening the crystalline structure of citrus fibers was limited, which might also affect the full action of enzymes in the later stage. After high-pressure homogenization and cellulase treatment, the microstructure of citrus fibers became loose and porous. The water holding capacity and swelling power of citrus fibers after high-pressure homogenization treatment were superior to other methods. The water holding capacity increased from 8.74 (g/g) in the control sample to 15.13 (g/g), and the swelling power increased from 5.23 (mL/g) to 18.21 (mL/g). The oil holding capacity of citrus fibers after high-pressure homogenization and cellulase treatment was superior to other methods, increasing from 3.64 (g/g) in the control sample to 17.13 (g/g).