Using the voluntarily disclosed customer information data from private enterprises listed on the Shanghai and Shenzhen A share from 2007 to 2021, the impact of major government background customers on private enterprises trade credit financing is examined from the supply chain perspective. The study finds that major government background customers significantly enhance the level of private enterprises trade credit financing; quantile regression results show that the promotion effect of major government background customers is stronger for private enterprises with a higher level of trade credit financing; and the test results of the mechanism of the effect show that major government background customers can strengthen product market competitive advantage, optimize the information environment of capital market, reduce the fluctuations in operating performance. Heterogeneity analysis show that the positive effect of major government background customers on private enterprises trade credit financing is more obvious in the period of stronger economic policy uncertainty, enterprises with higher supplier concentration and enterprises with poorer credit accessibility. The findings of this paper enrich and expand the functions of government procurement, with a view to providing a useful reference for optimizing the supply chain financing strategy of private enterprises and alleviating their financing difficulties.