In order to slove the problem of low root-soil separation rate and high damage rate of rhizome effect of Radix isatidi harvester, a type of combined swing rootsoil separation device for Radix isatidi was designed. The overall structure and working principle of the machine were described. Combining the planting pattern of Radix isatidi with the operational requirements of harvesters, based on the analysis of the dynamic of the root-soil complex on the sieve surface during the sieving process of the device, the main factors and their ranges that affected the effect of the root-soil separation were determined. The rootsoil separation rate and damage rate of rhizome were used as test indicators. The sieve surface inclination angle, crank rotational speed, and crank radius were the test factors, and quadratic orthogonal regression test was carried out. The regression mathematical model between the indexes and the factors model between the test factors and test indexes was established by response surface analysis method, and the influence of test factors on test indexes was analyzed. The structure and working parameters which affected the separation performance of the combined swing-type root-soil separation were optimized. The results showed that when the sieve surface inclination angle was 14.94°, the crank rotational speed was 440r/min, and the crank radius was 19.95mm, the root-soil separation rate was 97.19%, and the damage rate of rhizome was 2.66%. Field tests were conducted to verify the optimized data under these conditions, and the results showed that the root-soil separation rate was 96.09% and the damage rate of rhizome was 2.75%, which satisfied the operating requirement of Radix isatidi root-soil separation.Finally, field tests were carried out under the same conditions, and the results showed that the sieving effect of the sieve strip sieve plate combined sieve surface was better than that of the full sieve strip sieve surface and the full sieve plate sieve surface.