Abstract: Based on the author' s practice for more than ten years the concept of Interface Engineering (IE) was suggested firstly in the spring of 1991 , which included four parts; fertilizer engineering, feed engineering,food engineering and storage engineering. This paper pointed out the technical contents of each of the four kinds of engineering and discussed their positions and funtions in an agricul tural production system. Interface engineering can be used to coordinate the relationship between the system and its out environment, the relationship among the different economic departments of the system, and the relationship among the different elements within the departments. All these were illustrated in the favorable results of the interface engineering practice in 3 examples in the suburb of Beijing. The characteristics of IE, the target of its overall design and the way of adjustment and control were finally proposed.