Abstract: Capital structure is a financial tool that helps to determine how do firms choose their capital structure? a firms capital structure is then the composition or structure of its liabilities. In this study, an attempt has been made to analyze the Capital structure and financial performance during 2006 to 2010 (05 years) financial year of listed trading companies in Sri Lanka. For the purpose of this study, the data was extracted from the annual reports of sample companies. Correlation and multiple regression analysis are used for analysis. The results revealed there is positive relationship between capital structure and financial performance. And also capital structure is significantly impact on financial performance of the firm showed that debt asset ratio, debt equity ratio and long term debt correlated with gross profit margin(GPM), net profit margin(NPM), Return on Capital Employed(ROCE),Return on Asset (ROA) & Return on Equity(ROE )at significant level of 0.05 and 0.1.