Abstract: A plowing, leveling, and seeding integrated machine has been prevalently used in modern agriculture in recent years. However, the suboptimal soil backfilling and soil fragmentation can be caused along with the relatively high tillage resistance during operation. In this study, an attempt has been made to design the straight blade of the rotary tillage with the bionic dorsal fin structure. The inspiration was also drawn from the contour curve of the shark's dorsal fin. The unique biological features of the sharks were employed to enhance the performance of the agricultural machinery. The contour of the dorsal fin was analyzed to fit the Gaussian equation. A series of calculations was finally carried out to verify this bionic blade. The results show that the R² value was extremely close to 1, and the SSE value approached 0. The function equation and fitting were selected for the high accuracy of the data prediction. A precise fitting was more accurately represented for the contour of the dorsal fin. The bionic blade of the rotary tillage was obtained after representation. A quadratic orthogonal rotation experiment was conducted using the discrete element method. The rotary speed of the blade roller, n, the forward speed of the machine, v, and the tillage depth, h were selected as the influencing factors, while the backfilling rate, P, the soil fragmentation rate, I, and the tillage resistance, F were chosen as the evaluation indicators. The performance of the bionic blade was then obtained under different operating conditions. An optimal combination of the operating parameters was achieved for the contact model between the bionic rotary tillage blade and soil particles, where the rotary speed of the blade roller reached 241 r/min, the forward speed of the machine was set at 0.65 m/s, and the tillage depth was maintained at 120 mm. The bionic blade was also operated most efficiently in the optimal state. There was an excellent balance between soil backfilling, fragmentation, and tillage resistance. An indoor test was carried out on the soil trough. The performance of the bionic blade was validated after the test. The test results show that the backfilling rate of the bionic blade was 84.34%, the soil fragmentation rate was 79.7%, and the average tillage resistance was 87.25 N. The bionic blade demonstrated the remarkable advantages compared with the straight, curved, and chisel-shaped blade. Specifically, the backfilling rate increased by 11.98%, 36.62%, and 23.2%, respectively; The soil fragmentation rate was enhanced by 15.07%, 6.89%, and 10.32%, respectively; The tillage resistance decreased by 15.59%, 28.83%, and 24.38%, respectively. Additionally, the relative errors between each index and the simulation were 3.7%, 3.2%, and 4.5%, respectively, indicating a high degree of consistency between the simulation and the test. In conclusion, both the simulation and the indoor soil trough test indicate that the bionic rotary tillage blade effectively reduced the tillage resistance, while there was a significant improvement in the backfilling rate and soil fragmentation rate of the rotary tillage. The finding can also provide a valuable blueprint to optimize the strip rotary tillage device in agricultural machinery.