Abstract: This paper describes the studying course for national operational monitoring system of agricultural natural resources on large scale, especially for the national scale like China. The effective method was found to monitor the changes of agricultural natural resources for our country by means of the rational integrity of remote sensing technique and sampling theory. The efficiency and effectiveness were discussed and evaluated by the theory of total non-determinative degree and the relationships between the confidence limit and the precision for the method of drawing samples. Compared with the method existed abroad at present, the method described in this paper was proved not only to accelerate the industrialization of remote sensing application in agriculture, but also to widen the field of traditional sampling method.