The financing structure optimization of ESCO project is an effective way to improve the finance efficiency of company project. The paper summarizes the foreign new financing structure theory from four aspects: pecking order theory, agency cost theory, financial contract theory, signal theory; The new trend of project financing structure of domestic is discussed from project governance, systems analysis, financing income. Finally, Based on economic characteristics and research status of ESCO under energy performance contracting, it puts forward the research framework of financing structure optimization of ESCO project.