The economy clustering makes it possible to form a comprehensive look at the state policy of regional development, increase performance, efficiency and competitiveness of business, expand opportunities for innovative development, optimize interaction between various subjects: state, business structures, research and educational establishments and other organizations. As world practice shows, the cluster claims to be one of the key components of the competitiveness of the most progressively developing countries. A list of the most important threats affecting the sustainable development of the agro-industrial complex as a megacluster is presented in the paper: a strong dependence of agricultural sector efficiency on the areas of processing and trade, a high dependence of the agro-industrial complex on the market price condition, a high dependence of domestic agro-industrial production on the external food markets, etc. Critical analysis of literature on stability issues was carried out. It is determined that the existing definitions characterize the production process and its efficiency not significantly. This made it possible to clarify the existing interpretations and characterize stability as the ability of a production or business system to function stably for a long time, despite internal and external threats. Integral components of sustainable development are determined in relation to AIC as a cluster organization: production and economic development, social and economic development, territorial development and maintaining stability of the ecosystem. Own definition of sustainable development of the agro-industrial complex as a megacluster unit has been developed. An extended classification of forms and types of stability of the cluster arrangement of the AIC is proposed. Such systematization gives an objective idea of the multiplicity of stability issues and defines the AIC as a sophisticated megacluster system.