Dioscorea opposita Thunb. and Pueraria thomsonii Benth. starches were hydrolyzed with 0.36% HCl under ethanol conditions during 1, 3, 5, 8, and 12 h. Structural and physicochemical characteristics studies of C‐type D. opposita Thunb. and P. thomsonii Benth. starches were carried out using SEM, XRD, and FTIR spectroscopy. From the FTIR result, it was determined that the amorphous areas of starch granules were hydrolyzed successfully. The SEM and XRD results revealed that the interior was preferentially hydrolyzed and the degree of crystallinity increased for D. opposita and P. thomsonii starches. However, the two kinds of starches were hydrolyzed in different ways. The starch granules of D. opposita presented bread‐like in shape after acid hydrolysis. While the P. thomsonii Benth. starch granules were degraded for concaves formed on the surface, and several small particles appeared. Water‐binding capacity and AM content were observed to be lower for both starches. The thermal results revealed that the hydrolyzed starches showed the lower ΔHgel than the native starches, which can be related to the preferential destruction of amorphous areas in the granules.