The famous Three-Bivers Plain is located at junction area between the HeilongJiang, the Songhua Jiang and the Wusuli Jiang. It is now one of major reclamationareas in China.The present article tries to classify land types of the Three-Rivers Plain andto discuss chief measures for transforming the natural environment. It is based on afield work performed in 1978 on large-scale mapping of the Victory State Farm whichis located at eastern part of the Three-Rivers Plain. Then, by help of Land-sat images, 1/500,000 topographic mape, as well as field observations, a map ofland types or whole Three-Rivers Plain (1/500,000) was compiled in 1979.The term "land" is treated as the integration of all physical factors in a site,while landform, soil and vegetation are used as chief eriteria for classifying the landtypes. Four land types of first category (land system) and ten land types of secondeategory (Land units) are identified in the Three-Rivers Plain.Major measures for transforming the natural environment of the Three-BiversPlain are: (1) An over-all planning, with present emphasis laying on reelamationof arable virgin lands; (2) For an integrated use of all marsny lands; (3) To con-trol low temperature and frost hazards and to make better use of solar radiation;(4) To meliorate the whitish glei soils which are distributed extensively in the centralpart of the Three-Rivers Plain; (5) To conserve and to improve the broad-leavedforests in the surrounding hilly lands.