This paper, based upen the methedology of system Engineering,takes the Shanghai's specific statistic data as an example, illustrating how the Scientific and Technological (S& T) Jnput acts on the output of Gross National Product (GNP) trader the granted existence of macro-soctal-cecnomical loop.As China is lacking in relevant scientific data for the time being, the methods adopted and the cenclusions there after reached in the present paper may provide somcthing which is of some value to quantitative planning and decision.