化学背景与异常在统计学上的差异同时表现在浓度和变差两个方面。在划分背景与异常时，把这两方面信息提取出来并作显化处理，使背景与异常的差别更大，以利划分，这就是Ｃ型转换的基本思想。介绍了Ｃ型转换法的基本原理及其在条件模拟和实际金矿区中的应用。 The difference between the chemical background and the anomaly is statistically significant in both concentration and variability. In the division of the background and the anomaly, the two aspects of information extracted and made explicit treatment, so that the difference between the background and the anomaly larger, to facilitate the division, which is the basic idea of ​​C-type conversion. The basic principle of C type conversion method and its application in condition simulation and actual gold mining area are introduced.