An intra-row mechanical weeding device was designed. The device is one part of intelligent weeding machine. It has eight hoes that could turn in or turn out of intra-row area in the intelligent control system to eliminate the intra-row weeds. A 3-D parametric model of intra-row mechanical weeding device was built up with Pro/E, and was input ADAMS. The device was simulated on kinematics by ADAMS to get the track of each hoe. By analyzing the tracks, the area for each hoe with the superposition of adjacent hoe were figure out. Based on analysis result, the optimal proportion of rotation speed and forward speed was obtained (λ=0.754). Simulation proved that the device could satisfy the need of intra-row weeding.