In this paper, the hourly ERA5 reanalysis dataset and observation datasets from March 2018 to February 2021 are adopted to investigate the characteristics of the sea-land breeze over Tianjin area. Firstly, conventional methods are used to identify sea-land breeze events. Secondly, the annual averages and seasonal differences of sea-land breeze characteristics are analyzed and compared based on these two different datasets with the purpose to make an assessment of the applicability of the ERA5 reanalysis dataset. Similarities and differences are concluded as follows. (1) Both datasets are capable of revealing the fact that sea-land breeze events mostly occur in summer with similar distributions in all four seasons. The sea breeze lasts longer than the land breeze with stronger intensity. Both breezes reach their maximum intensities in spring. (2) Compared to results revealed by the ERA5 reanalysis dataset, the starting and ending of the sea breeze revealed by the observation data have a weaker bimodal structure which is not shown in the ERA5 data. The revealed starting and end time of the land breeze are ahead of their correspondences revealed by the ERA5 data. The duration hours of both the sea breeze and the land breeze are longer revealed by the observation data. (3) There are seasonal differences revealed by these two different datasets. The minimum intensity of the land breeze revealed by the ERA5 data occurs in summer, while the longest duration hour of the sea breeze occurs in autumn. The minimum intensity of the land breeze revealed by the observation data occurs in autumn, while the longest duration hour of the sea breeze is in spring and summer. It is found from the assessments that the ERA5 reanalysis data with the duration of three years are suitable for the future analysis of the sea-land breeze over Tianjin Circum-Bohai area.