This systematic review examines the global pollution of groundwater by microplastics (MPs) from 2017 to 2023. The study aims to provide a comprehensive overview of aquifers, sampling and analysis methods, pollution levels, polymer types, and sizes of MPs in groundwater. Despite increasing public concern and research interest, the number of studies on MPs in groundwater is relatively low compared to marine environments. The review identifies 201 research papers, with a focus on field activities and laboratory experiments. Key findings include: 1. **Global Research Trends**: The number of studies on MPs in groundwater has increased over time, but the focus remains limited to specific regions, particularly China, Korea, the United States, India, Australia, Germany, the United Kingdom, Italy, the Netherlands, and Mexico. 2. **Sampling and Analysis Methods**: Most studies used grab sampling methods, with varying sample volumes, and relied on equipment and containers that may contain plastics. On-site groundwater quality parameters and ion analyses were often not included, limiting the understanding of MP sources and behavior. 3. **Abundance, Polymer Types, and Sizes**: MP concentrations in groundwater ranged from 0 to 6,832 particles/L, with the highest concentrations found in shallow, unconsolidated aquifers near industrial and urban areas. Polypropylene (PP) and polyethylene (PE) were the most common polymers detected. MP sizes varied widely, and fiber-shaped MPs were predominant. 4. **Future Research Directions**: The review highlights the need for standardized sampling approaches, including optimal sample volumes and methods for purging and field blanks. It also emphasizes the importance of understanding the pathways and behavior of MPs in groundwater, as well as developing strategies for mitigating MP pollution. 5. **Conclusion**: Groundwater microplastic pollution is a significant global issue, and urgent research is needed to address the health and environmental risks associated with MPs. Standardization of sampling methods, understanding of MP behavior, and development of remediation strategies are crucial for sustainable groundwater management.This systematic review examines the global pollution of groundwater by microplastics (MPs) from 2017 to 2023. The study aims to provide a comprehensive overview of aquifers, sampling and analysis methods, pollution levels, polymer types, and sizes of MPs in groundwater. Despite increasing public concern and research interest, the number of studies on MPs in groundwater is relatively low compared to marine environments. The review identifies 201 research papers, with a focus on field activities and laboratory experiments. Key findings include: 1. **Global Research Trends**: The number of studies on MPs in groundwater has increased over time, but the focus remains limited to specific regions, particularly China, Korea, the United States, India, Australia, Germany, the United Kingdom, Italy, the Netherlands, and Mexico. 2. **Sampling and Analysis Methods**: Most studies used grab sampling methods, with varying sample volumes, and relied on equipment and containers that may contain plastics. On-site groundwater quality parameters and ion analyses were often not included, limiting the understanding of MP sources and behavior. 3. **Abundance, Polymer Types, and Sizes**: MP concentrations in groundwater ranged from 0 to 6,832 particles/L, with the highest concentrations found in shallow, unconsolidated aquifers near industrial and urban areas. Polypropylene (PP) and polyethylene (PE) were the most common polymers detected. MP sizes varied widely, and fiber-shaped MPs were predominant. 4. **Future Research Directions**: The review highlights the need for standardized sampling approaches, including optimal sample volumes and methods for purging and field blanks. It also emphasizes the importance of understanding the pathways and behavior of MPs in groundwater, as well as developing strategies for mitigating MP pollution. 5. **Conclusion**: Groundwater microplastic pollution is a significant global issue, and urgent research is needed to address the health and environmental risks associated with MPs. Standardization of sampling methods, understanding of MP behavior, and development of remediation strategies are crucial for sustainable groundwater management.