The general design model is attained taking the cotton barrel replacement robot as the research object using Solidworks to model and assemble the robot. The stress contour and displacement contour of the robot in workplace were obtained by analyzing the static characteristics of the cotton barrel robots terminal position under the maximum load condition using the ANSYS Workbench software. The fact that the lumbar rotary bracket is the weakest link was indicated after an integrated research of the distribution characteristics of the robot strength and stiffness. The conclusion is drawn that the maximum equivalent stress and displacement of the robot can be reduced to some extent by thickening the stiffening rib on the bottom rotary bracket and this can further improve the structure properties of the robot.