Abstract: This study investigates the effect of ownership structure on firm performance of listed manufacturing companies in Sri Lanka. The study was used secondary data for conducting this research. Ownership structure consists with two variables. Those are institution ownership and block ownership. And also researcher used some control variables. Return on Equity (ROE) was used as measurements to measure the firm performance. This study was used 20 companies for the analysis to achieve the set objectives. The Descriptive statistics, Correlation analysis and Multi- variant analysis were used in this study to analysis the data. The study found that the block ownership have negative and insignificant relationship with firm performance. Institutional ownership has positive and insignificant relationship with firm performance, and also firm size has positive and significant relationship with firm performance