Abstract: The seasonal rain forest is zonal vegetation type of north tropics in south Guangxi.The paper mainly deals with its classification and geographical distributional law in acid soil region of Guangxi. A.preliminary classification system has been set up in Guangxi.They are discribed as follw:1.Seasonal rain forest dominated by Dipterocarpaceae 1.1 Formation dominated by Hopea chinensis 1.2 Formation dominated by Shorea wangtiansue 2.Seasonal rain forest dominated by Myristicaceae 2.3 Formation dominated by Knema guangxiensis 2.4 Formation dominated by Horsfieldia amydalina 3.Seasonal rain forest dominated by Sapotaceae 3.5 Formation dominated by Eberhardtia aurata 3.6 Formation dominated by Madhuca subquincuncialis 4.Seasonal rain forest dominated by Burseraceae 4.7 Formation dominated by Canarium album 5.Seasonal rain forest dominated by Hamamelidaceae 5.8 Farmation dominated by Mytilaria laoensis 5.9 Formation dominated by Symingtonia tonkinensis 5.10 Formation dominated by Rhodoleia championi 6.Seasonal rain forest dominated by Leguminosae 6.11 Formation dominated by Lysidice rhodostegia 6.12 Formation dominated by Erythrophleum fordii 7.Seasonal rain forest dominated by Sterculiaceae 7.13 Formation dominated by Pterospermum lanceaefolium 8.Seasonal rain forest dominated by Myrtaceae 8.14 Formation dominated by Syzygium hancei

Key words: seasonal rain forest, vegetation, classification, formation, association, north tropics