Abstract: The historical development of agricultural soil water engineering is reviewed, and the content and the object of study of this special field of engineering are discussed. The main research topic should be the Soil-Crop-Water relationship and its adjustment and control. Its main task in the 21 century should consist of the following parts, i. e. the theory of mass transport and energy transfer in the field and the principle of their adjustment and control; mechanism of adverse circumstances to effect on crops and water management in water-saving agriculture; modern irrigation management and technology based on the theory of water relationship in soil-crop-atmosphere continuum; to improve field irrigation technology and to establish complex water-saving technology system in agriculture; irrigated land evaluation and land use improvement as related to sustainable land use; effective use and optimal management of agricultural water resources; environment problem of agricultural soil-water resources and so on. The trend of development of soil-water engineering in the 21th century, is also predicted. At last, some suggestions to promote the development of this field of engineering are presented.