<p>To improve the transmission accuracy and load capacity of non-circular gears, this study proposes a bionic tooth profile non-circular gear (BTP-NCG) design method based on the principles of biomimicry, inspired by the joint structure of a flea’s leg. Firstly, the Fourier series was used to accurately fit the bionic tooth profile, and a dedicated rack cutter was designed to achieve the gear design using high-precision generation methods. This study systematically investigated the mapping relationship between Fourier fitting coefficients and tooth profile geometry, as well as their influence on key performance parameters, including gear contact ratio, pressure angle, and sliding rate. Compared to traditional involute non-circular gears, the BTP-NCG exhibits significant advantages in terms of contact ratio, pressure angle, sliding rate, and contact stress. To validate the design’s effectiveness, prototype manufacturing was completed, and tests, including transmission ratio testing, angular displacement simulation, and tooth side clearance measurement, were conducted. The results showed that the simulated transmission ratio and angular displacement curves match the theoretical curves closely, and the tooth side clearance is reduced by up to 75% compared to the involute non-circular gear. Further application of the BTF-NCG in the seedling picking mechanism demonstrates that its motion trajectory matches the theoretical trajectory better than traditional involute gear planetary systems, confirming the feasibility and practical value of this design in precision transmission fields.</p>