Abstract: In this paper, the power spectrum and cross spectrum are calculated for the Yougshu reef, a marine meteorological observatory, of the Nansha archipelago, with the ocean-atmosphere elements during the summer (from May to August) of 1989. The results show that: (1) in the variation of meteorological elements, there are two low－frequency waves with 30－40 day and 15. 38 day periods, respectively; (2) as to the two low－frequency waves, there is an obvious lag correlation between pressure and wind, also there is clear correlation between low－cloud and wind velocity; (3) the water skin－surface temperature is characterized by quasi－two week oscillation and is correlated to two－cloud evidently. Finally, a discussion is made on the mechanism of synoptic dynamics and the ocean－atmosphere interaction of these correlations.