Mini tracked truck’s working unit is a device constrained by the dual parallelogram. This unit can make the goods remain translational during the process of loading and unloading so as to ensure the work process safe and reliable. Because the device is consisting of two parallelograms in series and using the rail to constrain its trajectory, the institutional force is very complicated. Therefore, this article uses statics method to analyze the force that acts on the working unit, establish the mechanical equations of the main arm cylinder and the lifting arm cylinder. The article respectively gives the simulation of the mechanical properties of the main arm cylinder during the loading process and the lifting arm cylinder during the lifting process basing on MATLAB. Research result provides a theoretical basis for the design of this type of working unit.