Abstract: The division of surface substrate mapping units is an important basis and premise for surface substrate survey and achievement expression. In the practice of s surface substrate survey in Xinhui-Taishan area of the Pearl River Delta, this paper integrates and draws lessons from the comprehensive disciplines of geology, ecology and soil science, etc., then according to the principles that the macro can be identified, mapped and drawn, and the naming can represent the composition, structure and physical and chemical properties of geological matrix units, and reflect the logical relationship of the development and evolution of surface substrate, etc, this paper explores and puts forward a set of classification ideas of surface substrate mapping units based on geological formations research, mountainous-hilly area in South China. According to the above principles, the surface substrate survey in Xinhui-Taishan area is divided into sixteen main surface substrate mapping units. The division scheme has reference value for improving the investigation and evaluation of surface substrate and the construction of natural resources investigation and monitoring system.