It is an important means to make the protective use of historical district through business model. Located in the southeast area of Xi'an, the Sanxue historical district is one of the most typical and representative historical district in China, and it is also one of the most mature historical areas of tourism commercial development. From the perspective of the activity population and the analysis of principal components analysis(PCA), the influence weight of the influencing factors on the degree of commercialization of the Sanxue historical district was determined, and the quantitative evaluation system of the commercialization degree of the historical neighborhoods of Sanxue historical district was constructed. The weight of influence factors was combined with and the degree of commercialization, to reach a judgement that there is a slight over-commercialization in the Sanxue historical district, and there is a worsening trend for the over-commercialization. Finally, in view of the analysis results of various factors and the degree of commercialization, this paper puts forward some suggestions for planning improvement. The method of quantitative research on the degree of commercialization of historical neighborhoods is of reference to related research and practice.