Abstract: With the horsepower of agricultural tractors, the design requirements of the parameters should be improved accordingly, such as the suspension device strength and lifting force of the tractor and so on.This article focuses on some content, such as improvement of cylinder support structure of vertical pressure model, improvement of detachable pull rod pin shaft tightening mode, design improvement of rear rear of of rear bar, a quick calculation method of suspension lift force based on the 3D model mechanism motion analysis platform and so on.