Decision analysis shows that decision rules that perform well under conditions of environmental uncertainty give more weight to negative outcomes than to positive outcomes. In other words, these rules show a conservative approach and tend to take potential risks seriously. Accounting conservatism makes bad news that is more important in the context of prudent decision rules more timely reflected, and this helps corporate managers and investors to better implement prudent decision rules. Therefore, the main goal of this research is to investigate Accounting conservatism forward-looking and defensive business strategies, and environmental uncertainty with an emphasis on the asymmetric timeliness model. For this purpose, a sample consisting of 1610 companies admitted to the Tehran Stock Exchange during the years 2009-2022 has been investigated using standard error clustering. In order to model environmental uncertainty at the company level, two different criteria have been used. The results of the research showed that forward-looking companies that face higher levels of environmental uncertainty have higher levels of accounting conservatism than defensive companies. Also, the results of the research showed that stagnant companies, which face higher levels of environmental uncertainty, have higher levels of accounting conservatism compared to alert companies.