Abstract: This paper has advanced a method of Functionalized Regressive Division(FRD),or Critical Regression Analysis(CRA)to determine the optimum dividing points or inflection points for the non-linear saltation models,according to the Functionalized Analysis,Parted Regression and Generalized Chow-test.The CRA's core is to compute a minimum root of combined mean of squared residuals of all critical regression models.A functionalized statistical analysis(FSA)has been done with the theory of General Linear Models(GLM)and the GLM procedure of SAS.This paper demonstrated a feasibility and practical application of the CRA with an economical study on schistosomiasis control.The CRA can help us to determine the infiection with significance.It is the only basis for studying on critical control of disease,evaluating and modifying the intervention approach with mathematical method.The CRA or FRD can be widely applied in other fields.