In view of the existing peanut picking device widespreadly used, which breaking rate is high, easy winding, and blocking, based on two-stage peanut harvest, this research studied the mechanisms of picking peanut pods during picking up and threshing, and determined the optimal parameters of picking device. An axial flow peanut picking device with screw bendingtooth was designed. The screw, bendingtooth and concave sieve worked together to separate peanut pods from plant, because screw possessed pitch angle and bendingtooth possessed elevation angle, plant in a circular and axial motion along the roller and then it was eliminated from the machine, which can keep high picking rate, low breaking rate, and avoid winding and blocking. The key components were designed and calculated. Introducing the structure and principle of operation of the machine, the key components’ parameters were confirmed by deeply theoretical analysis which made up the picking mechanism that had a great influence on picking effect. The peanut variety “Huayu 30” was selected as test material, and picking gap, feed quantity and rotating speed of cylinder were selected as experimental factors. Meanwhile, the peanut picking and breaking rate were selected as experimental indexes. Through orthogonal test, the mathematical model was established between the experimental factors and indexes and studied on the response surface optimization. The working parameters of picking performance were optimized. After verification test, the conclusion was obtained that the peanut picking rate was 98.96%, the peanut breaking rate was 0.88%. When the angle between bendingtooth and roller generatrix was 33°, the angle of bendingtooth was 60°, the angle between screw and roller generatrix was 23°, which met national standard and the need of production.