In this paper the seasonal variation and structural characteristics of the sea/land breeze in the northern coastal area of Shandong Peninsula are studied in two ways:one is the analysis of the observed wind data, and the other is numerical simulation and experiments.Firstly, the hour to hour wind data through the year 1984 at Longkou Meteorological Station and Yantai Oceanographic Station are analysed through energy spectra and hodograph.It is revealed from the analysed results that the effects of the sea/land breeze in the area are notable in spring, summer and fall, especially in May.However, in winter the effects of sea/land breeze are not obvious.because the cold noitherly is prevailing.Secondly, a two-dimensional non-linear model of primitive equations is used to study the sea/land breeze circulation in May in the area.The results of numerical simulation consist basically with the analysed results of the observed sea/land breeze.