本文讨论了自然系列地图编制中的一个重要问题--自然界线之间的统一协调。作者通过对自然界线的定性、定量研究，阐述了自然界线及其相互联系的特征。并在此基础上提出了自然系列地图轮廓界线统一协调的主要方法和措施。

The purpose of this paper is to study the unified harmony of natural boundaries. First, it describes the main characters of the natural houndaries and what the unified harmony of the natural boundariesis. Second, it gives qualitative and quantitative analyses to the relations among the natural boundaries. On the basis of analysing, the coincilent degerees of Lijiang series maps (geomorphology map, soil map, vegetation map, land resource map) have been calculated with the method of measuring information by using Entropy function. The result of calculation shows that there are close relations among the natural boundaries, and how to represent the rdat ions is the key problem of the unified harmony. Last, it discusses main measures of ensuring the unified harmony of natural boundaries. The author goes into more details with the reference map of the unified harmony of natural boundaries, which is one of the most important measures. Its contents, compilation and application are described in detail.