The economic realities in Russia, characterized by the intensification of uncertainty and risks in business environment, dictate the need to find and implement effective tools to ensure financial security of business. An important role in this process is assigned to the processes of planning sources of financial resources and managing a financing system of organization. Basically, these tasks lie in the plane of optimal capital structure theory. However, despite extensive theoretical base, there is still no common understanding about the optimal ratio between own and borrowed sources in the company's financing structure. The authors reviewed a methodological and practical aspects of optimizing capital structure in agro-industrial group of companies within the framework of ensuring and maintaining an acceptable level of financial security both in the short term and on the strategic horizon of its operation.