Abstract: The hydro-mechanical differential turning mechanism using hydro-mechanical infinite transmission theory is the new close double flow transmission mechanism being suitably made up of hydraulic transmission and gear transmission. The scheme design, parameter matching, performances analysis, calculation of rigidity and strength of this mechanism have been becoming the important project of this discipline. By establishing the relation formulas of transmission ratio of turning mechanism with hydraulic power distributing ratio and hydraulic system draining ratio, the reasonable numerical value range of hydraulic power distributing ratio was obtained. By adopting power flow charts, the power flow direction on turning mechanism of tracklayer was drawn under all running states. By comparing the numerical values and directions of two powers under all running states, the existing conditions of circulating power on mechanism and its influence on mechanism output were analyzed. The methods of design and transmission characteristic analysis of this kind of mechanism were provided.