The present systematic review was conducted by gathering the impacts of climate change on occupational heat strain, gathering risk factors that may increase susceptibility to climate-related occupational hazards, and gathering measures for controlling the impacts of climate change on occupational heat strain in outdoor workers. Materials and methods: In this study, three main databases PubMed, Scopus, and Web of Science were searched to find relevant literature on climate change and its effects using subject headings, appropriate Mesh terms and experts' opinion. Results: The evidence suggests an imprecise but positive relationship between climate change and occupational heat strain in outdoor workers, and the most likely mechanism involves dehydration, fatigue, dizziness, confusion, reduced brain function, loss of concentration and discomfort. Conclusion: With predictions of increasing temperatures, the baseline heat strain incidence data from this systematic review study in tropical and subtropical countries with low and middle income may be used to help stakeholders in policy-making, promotion campaigns, occupational health interventions, and choosing appropriate control methods. Strong evidence indicates that, to manage adverse effects of heat stress on outdoor workers, key factors include anticipating, recognizing, evaluating, controlling, researching, risk management, and applying suitable policy development may be useful tools.