The work aims to extract the millet SDF in the ultrasound-microwave (U-M) assisted enzymatic method during the experiment and optimize the extraction process, in order to improve the yield of water-soluble dietary fiber (SDF) in millet. According to the yield of millet SDF, microwave power, extraction temperature, extraction time and material-to-liquid ratio were tested by single factor, and the above-mentioned four factors were optimized by orthogonal test. The yield and physical properties of SDF extracted under this condition and conventionally extracted SDF were studied. The optimum conditions for extracting SDF from millet flour were: 550 W microwave power, 1∶25 material-to-liquid ratio, 55 ℃ microwave temperature, 20 min microwave time and 13.63% extraction rate, which was 46.88% higher than that of traditional enzymatic extraction. By measuring the physical properties of millet SDF, it was found that the ultrasonic-microwave treatment significantly improved the water holding capacity, swelling power and oil holding capacity of millet SDF, which increased by 24.79%, 25.16% and 15.74%, respectively. Ultrasound-microwave assisted enzymatic method can improve the yield of millet SDF and has a significant effect on its physical properties.