Abstract: A  method of hierarchical scaling analysis (HSA) is proposed for size distribution of firms. If the size distribution of enterprises in a region follows Zipf′s law, the hierarchy of enterprises will bear cascade structure, and can be described with a pair of exponential functions, including the number law and size law. A hierarchical scaling law can be derived from the exponential equations, and the scaling exponent reflects the self-organizing state of systems of firms. The procedure of hierarchical scaling analysis is as follows. First, examines the cascade structure of a system of firms. The hierarchy of firms should follow the hierarchical scaling law. Second, investigates the scaling exponent. The value must approach the unit (i.e.,  q →1). Otherwise, the system of firms departs from the optimum aim of self-organized evolution. The method is applied to the 100 largest firms of Weidong District, Pindingshan City, Henan Province, China. The results are revealing for recognizing and understanding the industrial structure of the city of Pingdingshan