Currently, the government regards preventing the risk of the real economy “de-realizing and virtualizing” as the main part of the economic work, in order to prevent the market risk brought by the excessive financialization of enterprises. This paper selects the A-share listed companies in China from 2008 to 2021 as the research sample data, and explores the impact mechanism of customer concentration on the financial asset allocation of enterprises, and the samples have passed the robustness and endogeneity tests to ensure the reliability of the benchmark regression results. The study finds that customer concentration has a significant inhibitory effect on the financial asset allocation of enterprises, and the results are more significant under the conditions of high earnings management, high financing constraints and low inventory turnover. Further, the study results show that customer concentration has a more significant inhibitory effect on the short-term allocation of financial resources by enterprises. This paper not only provides a theoretical basis for the study of the relationship between customer relations and corporate financial asset allocation, but also helps to clarify the dilemma of how the real economy and the virtual economy coexist and develop, and provides policy implications for preventing the market system reform of “de-realizing and virtualizing”.