Abstract: Missing data commonly occur in clinical trials due to various reasons. The occurrence of missing data will cause information loss of the original data， and reduce the robustness and validity of the research results. Therefore， how to adequately deal with missing data should be considered with caution in clinical trials. This article introduces the causes and types of missing data， as well as several common methodological approaches to addressing missing data， aiming to promote researchers’ understanding and improve the quality of handling missing data in trials. Nevertheless， the best way to deal with missing data is to prevent or reduce the occurrence of data being missing in clinical trials， rather than relying on post hoc statistical analyses.