Abstract: In this study, Tanquan millet (TQM) was used as the main raw material, and TQM was crushed to make TQM powder, which was then extruded and expanded using twin-screw extrusion technology. The optimum conditions for the extrusion process of TQM were obtained through one-way and response surface test analyses, using the pasting degree of TQM flour as the evaluation index. Characterization of TQM powder and TQM modified powder was carried out to observe the changes in microstructure, pasting characteristics, rheological properties and physicochemical properties. The final results of the one-way and response surface tests showed that the optimum process parameters for the TQM modified powder: screw speed of 20 Hz, water addition of 24%, extrusion temperature of 115 ℃, TQM powder particle size of 150 μm, and the degree of pasting under this condition was 92.92%. The microstructure of TQM modified powder was severely damaged, with almost no intact millet flour particles, mostly aggregates formed by proteins and broken starch granules. The aging resistance and cold thickening ability were enhanced, and the fluid properties remained unchanged. There was some loss of nutrients during the extrusion modification process, but the nutritional value was still at a high level and could still provide sufficient nutrients for the human body. The results showed that the physicochemical properties of TQM powder were improved and nutritious after extrusion modification, which could provide a theoretical basis for the TQM composite mixed grain products.