Mangrove forests are an important ecosystem type in coastal zones and provide a large variety of ecological functions, including biodiversity conservation, hurricane protection on the banks, and improved land creation. It is vital to recognize the conservation status of mangrove ecosystems, especially when considering the background of climate change and rapid urbanization. In this study, the protection status of mangrove ecosystems was analyzed based on maps classified from remote sensing and using gap analysis. The results showed that the total area of mangrove ecosystems in mainland China was 264 km², 61% of it covered by nature reserves. Among the provinces with major mangrove forests, Hainan had a relatively small area but a high proportion covered by reserves, while Guangxi and Guangdong had large areas but low coverage proportions. Among the three mangrove forest types, Rhizophora apiculata-Xylocarpus granatum and Rhizophora stylosa-Bruguiera gymnorrhiza had high proportions (> 90%) covered by reserves, but relatively small areas. In contrast, Kandelia candel -Aegiceras corniculatum-Avicennia marina had relatively low reserve coverage (52.6%), but a large area. Priority areas outside the reserves were identified, and an approach to nature reserve expansion and ecological redlining were proposed to further protect these ecosystems.