The overlap of literature in umbrella reviews can affect the reliability and accuracy of research conclusions, leading to results with a higher risk of bias. Therefore, it becomes crucial to assess the degree of overlapping and how to handle it. In order to avoid redundant calculations and reduce the risk of bias, researchers need to quantify the degree of literature overlap and adopt corresponding processing strategies. This paper provides a detailed introduction to the calculation methods of overlapping and different strategies for handling overlapping, aiming to provide a reference and guidance for domestic scholars' understanding and application of this method.