Traditional financial theories considered firms' financing strategy only from the perspective of debts' tax shield benefits and their financial distress costs, and overlooked the effects of high debt ratios on firms' sustainable development. High debt ratios not only affects firms' investing behavior and market competition behavior, but also affects the trading behavior of their stakeholders such as customers, suppliers, employees, creditors and shareholders. These could further affect firms' future development and survival. Based on the above considerations, firms should reduce their debt ratios accordingly to achieve more sustainable development when making their financing strategy.