As a ubiquitous emerging contaminants in our daily life, micro(nano)plastics (MNPs) have been proven to have an impact on human health. Due to the differences in the chemical composition, size, color, and shape of MNPs in the marine environment, researchers currently do not have unified standards for their analysis, identification, degradation methods, and toxic effects. This study provides a detailed introduction to the types and sources of MNPs, summarizes methods for collecting, separating, detecting, and identifying of MNPs in different sizes and different environmental media such as marine sediment and seawater. What's more, this study summarizes the biological effects and degradation mechanisms of marine MNPs. Most researches confirmed that MNPs can cause toxic effects on aquatic organisms, accompanied by time-dose effects. This study aims to provide reference for the future researches on the detection and treatment of MNPs pollution in the environment.