With Tianjin Doppler radar and auto-weather station data,the features and evolu-tions of 4 sea-breeze fronts are analyzed in Bohai Bay.It is shown that the echoes of sea breeze fronts of Bohai Bay belong to narrow and weak echoes and run parallel to Bohai Bay. Reflectivity intensity only remains 15-25dBz,its length about 100?00km,and its width changes with the weather and seasons.And its moving speed is very slow,just 10-15km·h^-1).It is proved that when a sea-breeze front meets a cold front,it can bring about severe weather.But only a sea-breeze front cannot cause severe weather such as shower,just mak-ing some changes in temperature, humidity,and wind direction.