In this paper, the mesoscale model WRF-ARW (Weather Research and Forecasting Model-Advanced Research WRF)(Version 4.0) is used to simulate a typical sea breeze front case in Hainan Island under different weather conditions with high numerical resolution. By designing sensitivity tests for local urbanization, the influence of coastal urbanization on sea breeze fronts in Hainan Island and its possible influencing mechanism are analyzed. The results show that the sea breeze front structure difference caused by urbanization is the result of thermal and dynamic effects. The friction effect of the underlying surface and the enhancement of urban heat island hinder the sea breeze from advancing inland, weaken the cooling and humidification effect of the sea breeze front, and result in a relative lagging of the sea breeze front. The high sea-land thermal difference caused by urbanization enhances the sea breeze wind speed and amplitude, and the vertical updraft and sea breeze circulation thickness in front of the sea breeze front are significantly enhanced. The influence of urbanization on the advance of sea breeze fronts varies during different stages of development. In the early stages of the development of sea breeze fronts, the driving effect of the thermal difference between land and sea is offset by the hindering effect of friction, resulting in no significant impact on the advance of sea breeze fronts. In the strong stage of development of sea breeze fronts, the thermal difference between inland cities and non-urban areas under urbanization conditions has increased, hindering the advance of sea breeze fronts towards inland areas, resulting in a decrease in the penetration distance of sea breeze fronts inland. The influence of urbanization on the advance of sea breeze fronts varies under different weather conditions. Compared to clear weather, the thermal difference between urban and non-urban areas under cloudy weather is slightly stronger, strengthening the hindering effect of urban heat island effect on the advance of sea breeze fronts towards inland areas, resulting in a slightly longer lag distance of sea breeze fronts. Furthermore, when land use transitions to towns occur, net radiation energy exchange with atmospheric air decreases leading to notable declines in latent heat flux alongside increases in sensible heat flux levels. This increased the underlying surface temperature, enhanced the vertical upward movement of sea breeze, and thus caused the increase in boundary layer height.