The temperature disparity between sea and land plays a pivotal role in assessing thermal distinctions, exerting a significant influence on regional and even global climate. This study utilized MODIS remote sensing data spanning from 2001 to 2021 to investigate temporal and spatial variations, as well as regional disparities, in land surface temperature, sea surface temperature, and the land-sea temperature difference in Eastern China. The findings revealed noteworthy increases in both surface temperature and sea surface temperature in Eastern China during 2001-2021, with increments of 0.34 ℃/10 a and 0.32 ℃/10 a, respectively. The upward trend in nighttime temperatures was more prominent. Seasonally, the significant magnitudes were observed in winter for surface temperature and in summer for sea surface temperature, each experiencing increments of 0.45 ℃/10 a and 0.43 ℃/10 a, respectively (P<0.05). Spatially, Eastern China typically exhibited a pattern of higher land surface temperatures in the southern regions and lower temperatures in the northern areas. Sea surface temperatures escalated from the northeast to the southwest, with near-shore sea temperatures being lower than those further offshore. The land-sea temperature difference in Eastern China consistently exhibited negative values, signifying that sea surface temperatures generally exceeded surface temperatures from 2001 to 2021. Moreover, the closer to the coastline, the smaller land-sea temperature difference the buffer zone. The interannual variation in land-sea temperature difference across the 100 km, 200 km, and 300 km buffer regions displayed a general declining trend, with the most substantial decline within the 100 km buffer zone. Seasonally, the land-sea temperature difference showed a decreasing trend in spring and winter, while an increasing trend in summer and autumn. Additionally, the land-sea temperature difference generally decreased in the north and increased in the south of 30°N.