Institutional has become very valuable in the implementation of sustainable agricultural development. The main objective of this study was to examine the dynamics of the system and the strategy of institutional sustainability of farmer groups in horticultural agribusiness in Bantaeng. Then, the collected data were processed and analyzed using qualitative descriptive with Brinkerhoff institutional sustainability analysis approach. The results showed that the dynamics of the system in changing inputs through the process to produce outputs consistently improved over time conditioning the institutional sustainability of farmer groups in the development of horticultural agribusiness in supporting sustainable agriculture. The contingency power of farmer groups is determined by their ability to respond to the dynamics of the work environment, as well as the political-economic environment through a combination of strategies, both mechanical, adaptive, reactive, and interactive carried out simultaneously or partially to achieve its sustainability level. The effectiveness of institutional sustainability strategies to support system capacity in improving farmer group performance, is indicated by its ability: (1) Creating competitiveness by maintaining product quality; (2) Handling and utilizing waste through innovation and development of product diversification so as to increase income, value added and environmentally friendly; and (3) Creating satisfaction for consumers.