Abstract: Based on basic element theory in Extenics and TRIZ(theory of inventive problem solving) functional model analysis method, an improved functional analysis method with two theoretical advantages is studied. First, the basic element and the TRIZ function model analysis method are expounded. On the basis of the full understanding of the two analytical theories, the process and steps of improving the functional analysis method are designed and expounded, and the concrete implementation process and application of the new method are explained and discussed with the toothbrush as a case. The improved functional analysis method has the characteristics of the formal representation and information mining of the basic element to the problem. At the same time, it has the TRIZ function model to express visually and vividly the structure and composition of the system. It is a more comprehensive and effective method of problem analysis.