Abstract: Aiming at the problems of incomplete pod picking and high pod breaking rate of the peanut picking device in the existing full-feeding type peanut combine harvester, a differential speed counter-rotating drum type peanut picking device for the full-feeding type peanut harvester was designed in this study. Peanut (Arachis hypogaea L.) is an annual herbaceous plant of the Leguminosae family in Rosales, which is the fourth largest oil crop in the world and one of the most important oil and cash crops in China, playing an irreplaceable role in safeguarding domestic edible oil supply and promoting the diversification of food consumption. China has long ranked first in global peanut production, yet the mechanization level of peanut sowing and harvesting operations still has a substantial gap with the actual production demand, especially the core pod picking link in peanut combine harvesting, where the widely used peg tooth drum type peanut picking devices generally have the prominent technical bottlenecks of incomplete pod picking and high pod breaking rate, which severely restrict the improvement of peanut harvesting quality and operational efficiency. Based on the working characteristics of the proposed differential speed counter-rotating drum type peanut picking device, a dynamic model of the interaction mechanics between peanut pods and the inner and outer picking drums was established, including the axial transport mechanics model of materials on the spiral blade of the inner drum, the force analysis model of pods under the action of the outer drum, and the collision damage mechanics model of peanut pods based on Hertz contact theory, and the structural parameters of the picking mechanism were optimized accordingly through theoretical derivation. According to the structural characteristics and working principle of the device, a discrete element contact model of the differential speed counter-rotating drum peanut picking device was constructed using EDEM software, with a calibrated bonded discrete element model of peanut vine and pods established based on the physical and biomechanical characteristics of the Yuhua 18 peanut variety, the main cultivated variety in coastal saline-alkali land. A three-factor three-level quadratic regression orthogonal rotation combination test was carried out with the feeding rate, inner drum speed and outer drum speed as the influencing factors, the value ranges of the test factors were deduced through theoretical calculation, and the peanut pod picking net rate and breaking rate were selected as the response indices of harvesting performance. Design-Expert software was used to establish the mathematical model between the response indices and the influencing factors, and parameter optimization was performed based on the response surface methodology. The simulation results show that the optimal working parameter combination of the device is as follows: feeding rate of 3.3 kg/s, inner drum speed of 438 r/min, and outer drum speed of 45 r/min, under which the simulated picking net rate reaches 99.11% and the pod breaking rate is controlled at 1.1%. The field comparative tests were carried out in strict accordance with the national standard GB/T 8097-2008 Harvesting machinery—Combine harvesters—Test methods, with the original peg tooth drum type peanut picking device as the control group, and the test results show that the picking net rate of the device reaches 99.02% and the breaking rate is 1.1%, which are significantly better than those of the original peg tooth drum type peanut picking device with a picking net rate of 98.18% and a breaking rate of 2.04%. The field test results are basically consistent with the simulation results, which fully verifies the correctness of the established simulation model and the reliable field operation stability of the proposed device. Both the picking net rate and breaking rate of the device meet the mechanized harvesting standard of peanut, and this study can provide a theoretical reference for the structural improvement and parameter optimization of the differential speed counter-rotating drum type peanut picking device, as well as the research and development of mechanized harvesting equipment for peanut.