Marshes are widely distributed in China and play a key role in regional carbon cycling. The Fraction of vegetation cover is an important indicator for evaluating wetland vegetation growth and carbon sequestration capacity. Currently, global climate change profoundly impacts the vegetation coverage of marshes, thereby affecting regional and even global carbon cycles. In the context of global warming, understanding the spatiotemporal change in marsh vegetation coverage and its response to climate change is of great significance for accurately assessing and predicting the carbon sequestration potential of marshes. Based on MODIS NDVI data and monthly meteorological data from 2001 to 2022, this study used the dimidiate pixel model to analyze the spatiotemporal changes of vegetation coverage during the growing season of marshes in China and their responses to climate change. The multi-year average of vegetation coverage during the growing season of marshes in China was 58.49% from 2001 to 2022. The vegetation coverage during the growing season of marshes showed a significant increasing trend (0.025/10a; P<0.01). The areas with the higher increasing trend in vegetation coverage during the growing season were mainly located in the Songnen Plain, while the areas with the higher decreasing trend were mainly found in the southwestern part of the Tibetan Plateau. The national average growing season vegetation coverage of marshes was significantly positively correlated with both growing season precipitation and minimum temperature, indicating that increases in growing season precipitation and minimum temperature could enhance marsh vegetation coverage. In different regions, the increase in growing season precipitation significantly enhanced the vegetation coverage in the marshes of the Northeast and Inner Mongolia regions; the rise in daytime maximum and nighttime minimum temperatures during the growing season had a strong positive effect on the increase in marshes vegetation coverage in the Tibetan plateau region, but the rise in daytime maximum temperature had a negative effect on the marshes vegetation coverage in the Inner Mongolia region. In terms of the influence of nighttime minimum temperature, the increase in the nighttime minimum temperature during July and August can significantly increase the vegetation coverage of marshes in the Tibetan Plateau region. The increase of September's nighttime minimum temperature can significantly increase the vegetation coverage of marshes in the most of China's marshes. Understanding the spatiotemporal variation of vegetation coverage during the growing season of marshes in China and its response to climate change can provide scientific evidence for assessing the carbon sequestration potential of Chinese marshes and reveal the mechanisms behind the relationships between wetland vegetation and climate change.