Actively constructing a financial center is an important approach for China’s local governments to develop the economy. Researchers mostly focus on the discussion of the formation conditions and radiation effects of financial centers. The existing literature seldom studies how developing countries avoid a duality finance structure by pursuing the development of regional financial centers while enriching the small and medium-sized bank (SMB) branches’ network in peripheral areas. In China, most financial centers in provinces (autonomous regions, municipalities directly under the Central Government) adopt the single-center mode, while a few adopt the multi-center mode. Taking the optimization of regional financial center layout and the enrichment of spatial structure of small and medium-sized banks in peripheral areas as the entry point, this paper uses the data of geographic location information of newly established bank branches of CBRC to study the path, mechanism, and variability of the development of business networks of small and medium-sized bank branches in peripheral cities influenced by the financial agglomeration of the center in different regional financial center construction models through the comparison of provincial single-center and multi-center, so as to illustrate the impact of regional financial center construction on the spatial pattern of financial resources. The paper first proposes a research hypothesis based on the model of central places of the new economic geography and the background of the construction of China’s regional financial center, and then constructs an empirical model of single-center and multi-center at the prefecture-level city level using data on the geographic location information of new bank establishments from 2006 to 2019 after the CBRC liberalized the market access of off-site branches of small and medium-sized banks. It is found that in the single-center model, the regional financial center has a siphoning effect on the financial resources of the peripheral prefecture-level cities, and the financial agglomeration of the central city inhibits the development of the business network of small and medium-sized bank branches in the peripheral prefecture-level cities, and the inhibiting effect decreases with the increase of the distance between the central city and the prefecture-level cities; in the dual-center model, the competition between the regional financial centers plays a moderating role in the inhibiting influence on the development of the peripheral financial spatial structure, which in turn weakens the siphoning effect of the single center. The higher the level of financial agglomeration in the dual center, the easier it is to form a common enhancement with the development of the business network of small and medium-sized bank branches in the peripheral prefecture-level cities. Further research shows that the difference in impact between single-center and dual-center layout patterns also exists at the county level. The inhibitory impact of the siphoning effect of the single center on the development of the operating network of various small and medium-sized bank branches in peripheral cities is universal, and the agriculture-related SMBs are even more affected. The fierce competition between the dual centers prompts small and medium-sized banks with local economic information advantages to prefer to set up branches in local markets, and with the occurrence of financial agglomeration in the center, the financial spatial structure of its peripheral cities is enhanced more rapidly. Compared with the existing literature, this paper mainly expands and deepens in the following two aspects. First, by applying the central place model of new economic geography to the analysis of financial practitioners’ utility in the context of regional financial center construction, the differences in the influence of regional financial center development layout on the development of financial spatial structure and the formation mechanism are studied. Second, for the first time, the siphoning effect of a single center on financial resources is determined at different levels of prefectural and county-level cities through empirical tests, eliminating the concern about the collapse of the financial spatial structure in peripheral areas under the multi-center development layout. Through the comparative study of the difference in the development of financial spatial structure between provincial single-center and multi-center, this paper summarizes the construction experience of regional financial centers in different regions of China for more than ten years, and provides a theoretical basis for the choice of regional financial center construction mode. With the gradual deepening of financial reform and opening up, adjusting the single-center model to multi-center is more helpful to play the role of the market, reduce regional financial inhibition, and optimize the spatial allocation of financial resources.