Road construction projects, as one of the vital pillars of infrastructure development, have always had significant impacts on the environment. These impacts, ranging from habitat destruction and pollution of water and soil resources to increased greenhouse gas emissions and climate change, have caused serious concerns. In this article, using a descriptive-analytical method and utilizing domestic and international resources, the legal study of environmental protection against road construction projects in Iran has been conducted. The main goal of this research is to analyze the existing environmental criminal laws and regulations in Iran, identify their strengths and weaknesses, and compare these laws with international standards. In this regard, first, key concepts such as sustainable development and environmental criminal law have been examined, and then, the status of laws and regulations related to environmental impact assessment (EIA), monitoring and enforcement of laws, and executive guarantees have been examined. Also, with a case study of road construction projects in Iran, the performance of these laws in practice has been evaluated. The results of this study show that although efforts have been made in recent years to improve the state of environmental laws, serious challenges remain in the areas of implementation, monitoring, and public participation. Finally, by providing policy proposals and implementation strategies, an attempt has been made to take an effective step towards improving environmental protection against road construction projects. This article can be used as a valuable resource for policymakers, researchers, and environmental activists to make informed and effective decisions in the field of environmental protection.