In the analysis and comparing of the chemical characteristics of precipitation in different areas, if we list the concrete data of all ions, it is very complicated and difficult to get the conclusion. In this paper, we suggest a simplified method to do it. First, we summarize some most important characteristics with representative alphabets, then divide these characteristics into different levels with representative Arabic numerals. By using a group of this kind of alphebets and numerals, we can describe and compare the main chemical characteristics of precipitation in different area. Based on the generally used observed data, we analyse and compare the typical chemical characteristics of precipitation in the three main acid rain areas.