Sometimes planes may dash out of runway when taking off and landing. In order to ensure the safety of the planes, we should take care of safety precautions in planning and design of airdrome. In this paper, a mathematical model of the plane-wheel and arresting system of sand is built. Through this model，in combination with terramechanics theory and the practical factor that the drag load of wheels should conform to the design range of undercarriages，the paper has discussed the buffering zone in detail in designing formula and approach. Also the geometric design requirement and design steps of the buffering zone are summarized, and the feasibility of the designing method is verified by living examples, which provide a theoretic foundation on the mechanics performance and independent development for the further research on soft-ground arresting system.