对南沙海区部分站位微表层和次表层的ｐＨ、碱度、密度和表面张力进行了测定。结果表明：微表层的表面张力低于次表层的表面张力，并且表面张力与溶解有机碳（ＤＯＣ）相关；微表层的ｐＨ低于次表层的ｐＨ，并探讨了其原因；微表层的碱度和密度一般高于次表层，同时对其原因进行了探讨。 The pH, alkalinity, density and surface tension of micro-surface and subsurface layers of some stations in Nansha sea area were measured. The results showed that the surface tension of the surface layer was lower than that of the subsurface layer and the surface tension was related to dissolved organic carbon (DOC). The pH of the surface layer was lower than that of the subsurface layer and the reason was discussed. And the density is generally higher than the subsurface, at the same time the reason is discussed.