Extrusion treatment at low moisture contents (10%, 15% and 20%) was used to prevent agglomeration during rehydration of kudzu powder, which seriously affects its instant properties. By extrusion, the agglomeration rate of kudzu powder decreased from 42.41% to 0.84%–1.46% when rehydration time reached 60 s. The sharp pressure drops during the extrusion process caused puffing of the powder, thereby reducing its bulk density, which facilitated rapid penetration of water into the powder. In addition, extrusion treatment destroyed the granular and crystalline structures (long-range and short-range) of kudzu powder, and reconstructed it into large particles with amorphous structure. Because of these changes, the wettability, including the water absorption and water solubility of kudzu powder, was remarkably enhanced, and thus the agglomeration problem was solved. Furthermore, extrusion treatment decreased the strength and consistency of kudzu paste and altered its color. The degree of these changes was related to the moisture level used in the extrusion process. Increasing the moisture content of extrusion was beneficial to maintaining the natural color of kudzu paste but was not conducive to maintaining its natural viscoelasticity. Display omitted •Extrusion significantly improves the instant properties of kudzu powder.•Extrusion caused puffing of kudzu powder, thereby reducing its bulk density.•Extrusion reconstructed the granular and crystalline structures of kudzu powder.•Extrusion enhanced the water absorption and water solubility of kudzu powder.•Viscoelasticity and color of kudzu paste were related to moisture level of extrusion.