This paper is intended to comparatively analyzed the KDC/NDC/DDC classification system for the field of civil engineering, the research field classification system of National Research Foundation of Korea, and the science and technology research field classification system of Korea Science and Engineering Foundation. And based on the analysis, it tried to propose the ways of improving the KDC classification system for the civil engineering field. As a result of the analysis, this paper has found that the KDC 5th-edition for the civil engineering field needed some corrections. That is, the classification items that reflect the trend of academic development should be added, the classification terminology of the basic theories of civil engineering should be properly developed, segmented topics should be added, any errors in classification codes and Korean/English descriptions should be corrected, and the omission of the KDC relative index of classification items should be solved. This paper proposed the ways of improving those problems.