Based on the hourly meteorological data from 27 automatic meteorological stations in Jinjiang and its surrounding areas in 2017, the diurnal variation of urban heat island intensity in Jinjiang in 2017 and the influence of sea-land breeze on urban heat island intensity were analyzed. Moreover, the influence of sea-land breeze speed in different seasons on the urban heat island intensity was also studied. Finally, the diurnal variation characteristics of urban heat island in Jinjiang were verified by a typical day with sea-land breeze. The results show that the annual average heat island intensity in Jinjiang City has a V-shaped diurnal variation trend; the sea breeze cools the city, and weakens the urban heat island intensity,while the land breeze can significantly enhance the heat island at night. Thus, the durinal variation of the heat island intensity at the day with sea-land breeze increases, compared with the day without sea-land breeze. The heat island intensity is negatively correlated with the sea-land breeze speed. The faster sea-land breeze speed can alleviate the urban heat island to some extent.