Green finance increases the innovation potential of green transformation, helps to address climate change, the environmental crisis and energy security. It is important for green finance to achieve sustainable and balanced development, which will increase the security of both finance itself and many processes in the real economy that depend on it. The purpose of this study was to develop approaches to the ontological design of green finance and multi-agent modeling of the behavior of green finance actors, considering their sustainable and safe interaction. To achieve this goal it was necessary to clarify the conceptual apparatus of green finance and related areas; to characterize the "work" of the multi-agent model in the analysis of the behavior of the main green finance actors and to trace the prospects for their impact on the stability and security of the financial market; and finally, based on ontology construction and agent-based approach to nonlinear interactions in the green financial process, to determine the mechanism of building chains of the main market participants. The methodological basis of the study consists of general scientific research methods (analysis, synthesis, induction, deduction, logic), as well as evolutionary dynamics and agent-based approach to the analysis of financial markets. A comparative analysis of the works of various authors and the interpretation of theoretical provisions in related areas of knowledge about finance, as well as the analysis of their sustainable and safe development were carried out. As a result of the study, the authors identified the main approaches to the design of financial ontology and multi-agent modeling of financial interactions in the direction of determining their sustainable and safe development. The proposed model establishes that the criterion of the effectiveness of the applied strategy is the satisfaction with the state of financial impact on the economy, environment, and social sphere. Maintaining this state, along with saving the amount of resources used, is done through optimization. The chosen approach corresponds to the concept of sustainable development and safe functioning of the systems under consideration.