Abstract: In supply-side structural reform, investment linkage is an important means to drive the "financial services real economy" and promote "combination between industry and finance". Further, the rational investment structure becomes the key to explore the "financial resource allocation efficiency" in investment linkage. According to statistics, from the beginning of 2016 to the end of June 2017, a total of 8.389 billion yuan of loans have been issued and 373 enterprises have been served through the investment and loan linkage financing in Beijing. By the end of the second quarter of 2017, the balance of investment and loan linkage was 4.802 billion in Shanghai, which is 78.93% growth compared to 2016. The bank actively carried out investment and loan linkage business and built a good cohesion way for industrial and financial capital. On the one hand, banks rely on "equity" investment finance to penetrate deeper into the real economy and achieve a close integration of finance and the real economy. On the other hand, equity investment further optimizes the financial structure of enterprises, enhances the ability of corporate debt financing, and effectively alleviates the financing dilemma of small and medium enterprises. Based on the realistic background, the article attempts to explore the "investment and loan linkage interval" and the optimal investment structure that could coordinate the maximization of the interests of investors by the retailer's robust risk model. This provides a theoretical reference for supply chain operations and financial integration. The paper overcomes the disjunction between investment decision and enterprise capital structure in previous studies. Firstly, a retailer investment and loan linkage financing model is constructed, and then the new characteristics of investment institutions participating in the game are described. Finally, the optimal investment structure and its influence on the decision-making of supply chain operation are discussed through mathematical deduction and numerical analysis. The investment and financing sides play the Stackelberg game, and the investors (banks and private equity) are leaders. The investor first makes the equity proportion (φ) to pursue the expected net investment return maximum, and then the retailer makes the robust decision with conservative net asset maximization when only knowing the information of market demand. Among all distributions that satisfy the mean value of μ and the variance of σ², it is found that the expected net assets of retailers are minimized (the worst distribution), and the optimal effort level e and order quantity q is determined to meet the expectation maximization. It is found that there exists the "investment linkage interval" and the optimal investment structure and the optimal investment structure is dominated by market growth. Moreover, lower corporate income tax has reduced the debt tax shield effect, there is an investment preference for "anti-pecking order".

Key words: investment linkage, operational perspective, investment structure, retailer