2.79％。In order to improve the operation performance of 4HLB-2 peanut combine harvester, the impact factors including soil moisture content, harvest time, stalk clamping height, clapping frequency and amplitude of clod removing unit, rotate speed of peanut picking roller and clamping chain speed were investigated by single or double factorial experiments. The results show that soil moisture content ranging from 8% to 15% is suitable for peanut harvesting in sandy loam soil. Dropped peanut loss during clod removing increases gradually along with the delaying of harvest time. The dropped peanut loss rate is higher than 2% under the snap force of peanut root below 5N. The optimum stalk clamping height is in the range from 150mm to 200mm, keeping total loss rate and clod content less than 6% and 4%, respectively. Lower frequency and smaller amplitude of clod clapping operation contributes to smaller dropped peanut loss rate, but higher clod content, whereas, higher frequency and larger amplitude contributed to lower clod content and higher dropped peanut loss rate. The peanut loss of peanut picking operation is kept at lower level with higher picking roller speed and lower clamping chain speed. In this experiment, loss rate of peanut picking is 2.79% at 390r/min of picking roller speed and 0.5m/s of clamping chain speed.