本研究採用應收帳款收現天數及應付帳款付現天數兩項財務變數作為顧客關係強度及供應商關係強度的代理變數（陳尚武等，2018），並以迴歸分析來檢定顧客關係強度與供應商關係強度對於固定資產比率、負債佔股東權益比率、賺取利息倍數等三項重要長期償債能力指標是否造成優化或弱化的影響。實證結果顯示，顧客關係強度越強，企業之固定資產比率及賺取利息倍數皆會越弱，而負債佔股東權益比率則會越高，惟顯著性皆呈高度不足現象。至於在上游供應商方面，結果顯示關係強度越強，企業之負債佔股東權益比率會越高而賺取利息倍數會越低，但顯著性亦皆不足。然值得注意的是，供應商關係強度越強，企業之固定資產比率會呈現極為顯著的弱化。本研究的結果可提醒企業在維繫強化供應鏈關係時，應謹慎評估所需的資本投資計畫案之風險與報酬，並採行適切的融資計畫支應，切莫過度浪費投入、破壞最佳資本結構，傷害了企業價值。

Armed with Chen et al. (2018), this study uses days sales outstanding and days payable outstanding as the proxy variables for customer relationship strength and supplier relationship strength respectively, to explore whether these two strengths have impacts on companies' long-term liquidity. Our regression analysis findings show that the stronger the customer relationship is, the lower the fixed assets ratio and the times interest earned but the higher the debt to equity ratio will be, all without significance. On the other hand, our findings also show that the stronger the supplier relationship is, the higher the debt to equity ratio but the lower the times interest earned will be, without significance for both; The impact on the fixed assets ratio, however, shows rater significantly negative. This study's findings highlight the key role of financing fixed assets investments plays on enhancing companies' supply chain relations. In addition to the comprehensive evaluation of risk and returns of the fixed assets investments committed, the prudent selection of their corresponding financing plans will help maintain the optimal capital structure and avoid the deterioration of companies' value.