Peanut breeding in mini area has the characteristics of various varieties, many deals in mini area, little yield and no mixed peanut in mini area and in variety. In order to solve the problems of time and working consuming, lower efficacy and easy to mix in artificial harvesting, an overall scheme of semifeeding peanut picking device was proposed. The structure of staggered matched stack form and the picking parts, including reinforced type, bow tooth and rectangular tooth with adjustable swing diameters were adopted. The structure and parameters of peanuts picking parts were designed. Preliminary experiment was carried out for choosing eventual form of picking parts. The main peanut varieties “huayu30” in Liaoning province were selected as test materials, through orthogonal experiment analysis, the three parameters: picking roller rotating speed, angle of picking roller and overlap distance of picking roller were selected as experimental factors, peanut picking rate and peanut breaking rate were selected as experimental indexes. The structure and working parameter of threshing performance were optimized. Experimental results indicated that picking roller rotating speed, angle of picking roller and the overlap distance of picking roller all had significant impact on peanut picking rate and peanut breaking rate. The most optimum combination index of the picking roller rotating speed was 400r/min, the angle of picking roller was 45° and the overlap distance of picking roller was 10mm. The results of the analysis of the peanut picking rate was 9896% and the peanut breaking rate was 1.03%.