Hainan Island lies between lat.18°09'一20°02'N and 1oog.108°36"-112°02'E.Its sea temperature at surface is rather high, the February monthly mean is 22℃ while August is 29℃. Both of its seasonal and annual variations are small. The types of tides are irregular or rather mixed, the tidal range is not over 3 m usually. Taking Maling (Yaxian) as an exemple, basing 'On the principles of Vaillant，we have discussed the zonation of the rocky coast between tide marks of Hainan Island. The belt from the highest high water (H. H. W.) to the lowest high water (L.H.W.) is called upper littoral belt, that from L. H. W. to highest low water (H.L.W.) is called mid-littoral belt, whereas that from H.L.W. to datum point is called lower littoral belt. Judging from the different cases each belt may be subdivided into several sub-belts.