Capital structure is the important part of the business performance. Here paper investigates the theories of the capital structure on the basis of review, from the start-up point. The focus and considered from Modigliani and Miller’s capital structure irrelevance theory to recent theories, such as the pecking order and the market timing theory. There are various studies which have examined capital structure determinants also in the corporate finance literature. The famous theories on capital Structure are Pecking Order, Trade off theory and Agency Theory. As per these theories there are various determinants such as assets structure, profitability, growth opportunities, liquidity, company size, and dividend policywhich affect the leverage of the firm, these are possibly responsible for decision making of the capital Structure, and find that pecking theory in capital structure decision prevails in the market, but some time moderate support for the trade-off theory.