The construction of artificial islands causes numerous environmental damage in addition to their positive consequences. The construction of artificial islands by the Caspian littoral states has caused this issue to be pursued more sensitively by Iran, and in such circumstances, the environmental and legal consequences of this issue should not be overlooked. In addition to environmental pollution caused by human activities and improper exploitation of nature, water pollution in the Caspian Sea region is a major part of the marine ecosystem health crisis of this region. Although some neighboring countries are trying to increase their share of land ownership by creating artificial islands for their economic, tourist and commercial activities, the establishment of these structures in the Caspian Sea is disrupting the health of the natural ecosystem of the Caspian Sea. The health text of the Caspian Sea ecosystem and Iran's protest against the construction of an island in the Caspian Sea due to their environmental issues has been analyzed in accordance with international law, Malaysia v. Singapore, the Netherlands v. Russia, and the international responsibility of states. The findings of this study show that in accordance with the international law of the sea, the construction of artificial islands is not prohibited, but their creation according to international jurisprudence is subject to respecting the rights of neighboring countries and assessing their environmental damage and informing neighboring countries. This research is of theoretical type, its research method is descriptive and analytical and its data collection method is library and with reference to international documents, books and articles.