Abstract: In response to the problems of low inter-row weeding rate, high seedling injury rate and difficulty in mid-tillage weeding operation of the existing weeding device under the three-row dense planting pattern of soybean on monopoly, a soybean inter-row weeding device for three-row dense planting on ridge was designed, which is mainly composed of positioning disc, popping teeth fixed linkage and popping teeth, etc. According to the growth state of soybean seedlings and weeds during the mid-tillage period, the installation distance of the positioning disc and weeding device was determined; The kinetic analysis of the weeding process of the popping teeth was carried out to establish the curve equation of the entry part of the popping teeth, and the kinematic analysis of the popping teeth was carried out. The Box-Behnken multi-factor test was conducted by using the discrete element simulation method with the number of circumferential tooth groups, the angle of entry of the teeth and the number of axial teeth as the test factors, and the loosening rate and the average working resistance of the teeth as the indexes, and the best results were obtained when the number of circumferential tooth groups was 10, the angle of entry of the teeth was 80° and the number of axial teeth was 5. A single-factor field performance test was conducted on the weeding device using the forward speed of the machine, the rotational speed of the weeding unit and the depth of entry as test factors, and the weeding rate and seedling injury rate as evaluation indexes. The results showed that the average weeding rate and seedling injury rate were 88.24% and 2.77%, respectively when the weeding depth was 35 mm and the forward speed of the machine was 2.5km/h. The operating performance of the machine was stable and no blockage occurred, which met the agronomic requirements of soybean inter-row weeding.