The main body of Quaternary Dongting basin, northwestern Hunan Province,is composed of Anxiang sag, Chishan uplift and Yuanjiang sag from west to east. The ZKC1 borehole was carried out at Lianghucun in southeastern Anxiang sag. The Quaternary sediments were composed of the Early Pleistocene Huatian Formation and Miluo Formation, the early—middle Middle Pleistocene Dongtinghu Formation, the Late Pleistocene Potou Formation and Holocene. The heavy minerals from the core of the borehole were analysed by the numbers. Based on the source and contents variations of diagnostic heavy minerals and combined with lithological and petrographic variations, and regional geologic and geographic backgrounds, the writers probed into the evolutions of the sedimentary environment and tectonic subsidence of the southern Dongting basin during Early and Middle Pleistocene. The studies show that there existed episodic faulted subsidences in the Dongting basin, and there existed three violent subsidences apart in early Early Pleistocene, last stage of Early Pleistocene and middle—late Middle Pleistocene; when the relative lakelevel rose, and thus partial water of the Zijiang River got west toward into Anxiang sag, which caused notable raises of the contents of heavy minerals came mainly from the Zijiang valley in the low part of lower Huatian Formation, the top of Miluo Formation and the upper Dongtinghu Formation, such as zircon, rutile, anatase and siderite. The subsidences were weak and the river—lake levels were low in other epochs, which led the water of the Yuanshui River to the west of Chishan uplift and the water of th e Zijiang River to the east of Chishan uplift flow into the Yangtze River along their primary flume respectively, and thus the contents of zircon, rutile, anatase and siderite in corresponding sediments in ZKC1 borehole were lower. Studies about the relationship between characteristic indexes of heavy minerals and paleaoclimate variations indicated by pollens and chemical index of alteration show that the main cause of the three raises of relative lakelevel is subsidence strengthening but not precipitation increase.