The wheel Skid-steer Loader is a practical and efficient, multifunctional small construction machinery which is often used for small spaces. It's walking steering action is mainly achieved with turning by the speed difference between the two sides of wheel, which is driven by a hydraulic motor. Through the analysis of the ZHL3210 type Skid-steer Loader, and based on the study of vehicle groundbased mechanics theory, the model of Loader's pivot turning was established, the principle of pivot turning of wheel Skid-steer Loader and power characteristics of the system were analyzed. It establishes a mathematical model of walking hydraulic system during pivot turning process.