Traditionally evaluation knowledge is integrated with land evaluation software by tight mode or loose mode. It can not meet the needs that the land evaluation systems can be organized at will in different cities, and entities such as factors and samples can be analyzed by different methods or processes. The evaluation knowledge's classifications, expressions, storage, integrated mode and the relations with data entities are discussed, and the evaluation repository is designed. Three types of evaluation knowledge: descriptive knowledge, rational knowledge,process knowledge are divided into several subsections such as entities, database structure, fields content, formula parameters and calculating methods etc. They will be expressed as strings and saved in the repository file.