Today the role of using management accounting techniques in improving the stability of companies' performance, making managerial decisions and flexibility in the face of environmental changes is in the center of attention. But the existence of unfavorable economic conditions causes disruption in this process, also the firm size as an organizational variable is effective in the power of coordination and compromise against environmental changes. Therefore, the current research studies the effect of implementing management accounting techniques according to the triple approach (operations-management-strategy) on the stability of the companies' performance, focusing on the simultaneous moderating effect of the inflationary stagnation situation and the firm size .For this purpose, the model of Erokhin et al. (2019) has been used to measure and classify management accounting techniques The results of the research based on the data analysis of 117 Manufacturing companies admitted to the Tehran Stock Exchange for a period of 8 years (2013-2020) using the structural equation modeling approach show that the firm size has a significant effect on the relationship between the use of management accounting techniques and the Sustainability Performance in during the Inflationary Recession Period and the Pre-Recession Period. also, the effect of firm size on the relationship between management accounting techniques and Sustainability Performance in the Per-recession period is greater than the inflationary recession period, because large companies use more operational techniques such as cost control, pricing and budgeting, etc. And less attention to the uses of management performance techniques and strategic techniques.