There are many time-honored firms in Xicheng District, Beijing. These old firms bring a strong sense of history and culture to Xicheng District. Because of their low proportion of the economy in Xicheng District, the measurement of time-honored firms' economic value is more focused on their 「overflow」 values to the whole society. Based on public goods and externalities theory, this essay analyzes the spillover values provided by those old firms beyond their business purposes and the spatial distribution of these values. This paper also uses willingness-to-pay survey to reflect people's views on the time-honored firms. From the geographic perspective, this article provides suggestion that urban planning should take the protection and development of time-honored firms' spatial layout into overall consideration, and meanwhile promote time-honored firms to extend their industrial chains to achieve cluster development by planning. Long-term goal of these measures is to better play time-honored firms' central leading role in regional development, business transformation and industry chain extension.