Based on the daily temperature data and Landsat satellite remote sensing data in Dazhou City from 2020 to 2024, the annual trend and seasonal variation characteristics of the urban heat island effect and vegetation coverage in the main urban area of Dazhou City over the past 20 years were analyzed and discussed, and the influencing factors of the urban heat island effect were explored. The results show that the urban heat island effect in Dazhou City has generally shown an upward trend in the past 20 years, and among all seasons, the increase is the most obvious in summe, with a growth rate of 3.36 °C per 100 years and a mean intensity of 0.553 °C. In contrast, the weakest heat island effect is in spring, with a growth rate of 1.43 °C per 100 years and a mean intensity of 0.457 °C. There has been a decline in vegetation coverage in urban areas. The influencing factors of the occurrence and change of the heat island effect are complex and diverse, which are not only affected by natural factors such as natural landform, geographical location, and climatic conditions, but also affected by activities associated with urbanization, such as urban development and construction.