In order to clarify the effect of extrusion processing technology on the physicochemical properties of tartary buckwheat flour, the influence of the different extrusion temperature, material moisture and screw speed to the water absorption index, water solubility index, swelling power, pasting and gel properties of extrusion tartary buckwheat flour was studied. The results showed that: compared to the unextruded tartary buckwheat flour, the extrusion buckwheat flour at 30 °C water bath has a better water absorption and water solubility, whlie the water solubility in water bath at 100 °C increased, the water absorption decreased, swelling power, pasting and gel characteristic values increased significantly. With extrusion temperature increase, the water absorption index, water solubility index and swelling power of the extrusion tartary buckwheat flour changed little, but peak viscosity and attenuation value increased, trough viscosity and setback value decreased, the quality of gels become better; with the moisture content increase, the water absorption, swelling power and the pasting characteristic value increased obviously, water solubility reduced significantly, and quality of the gel formation in low moisture content was good; with the screw speed increase, water solubility increased, but the water absorption, peak viscosity, trough viscosity and attenuation value reduced slightly, swelling power increased first and then decreased, and gel quality of the higher screw speed tartary buckwheat flour is better. Overall, the greatest impact on the properties of extrusion buckwheat flour was the material moisture. Water absorption index and water solubility index were significantly correlated with pasting properties and gel properties (P <0.05). The swelling power and pasting properties were significantly positively correlated(P <0.01), and there was no significant correlation between the swelling power and gel properties.