Introduction: The application of standards at each level of care in intensive care units has been a significant issue in recent years. The purpose of this study was to determine the standards of care levels in intensive care units. Methods: In this systematic review, all articles published in English from 2019-2001 and Persian sources in the period 2000-2009 were searched. On the standards of care levels of ICUs conducted at home and abroad, in databases such as Magiran Database, Sid, PubMed, Google Scholar, Science Direct was reviewed. The search resulted in 109 articles and research projects related to the subject, of which 10 were finally included in the study. Results: Each level of intensive care unit has certain standards in terms of structure, manpower, processes and equipment. It is recommended that, based on the level of specialty care provided, the type of services, equipment, manpower and processes be implemented in accordance with national guidelines in accordance with the standards of each level. Conclusions: Of the 10 studied, 4 were descriptive-analytical, 4 were descriptive-cross-sectional, one was analytical (10%), and one was a cohort study (10%). There were no intervention studies. There were 2 studies (20%) in India and 6 studies (60%) in Iran, one study (10%) in Canada and one study (10%) in the Netherlands. In addition, there were five factors: "physical spaces", "technology used in these units and monitoring of their accuracy", "manpower", "special services provided" and "education and research capability " as the underlying standards are central to determining the level of intensive care units.