In order to comprehend the terrestrialization situation and its driving factors in Lake Nansi, the whole Lake Nansi and 21 inlets of the rivers entering the lake were sampled and investigated in August 2008,June 2009,August 2009,June 2010 and August 2010.The results showed that only 4 sites located in the Natural Reserve of Weishan Island and the inlet of Jiehe River with dense shipping belonged to no terrestrialization,2 sites lying the inlet of Laowanfu River with busy transport and the open water region of Nanyang Lake to slight terrestrialization,other 6 sites were moderate terrestrialization, 12 sites severe terrestrialization and 1 site heavy severe terrestrialization among the 25 sampling sites.The degree of terrestrialization was significantly positively correla-ted to vegetation types,depth and organic matter content of silt,negatively correlated to pH and dissolved oxygen;the abundance of vegetation was close negatively correlated to depth of water,pH and dissolved oxygen;the silting level was positively to total ni-trogen,total phosphorus, organic matter of sediment,negatively to chemical oxygen demand.So apparently the import of exogenous contamination and increase of trophic level promoted the terrestrialization speed,and the unreasonable development in the whole drainage area further accelerated this progress.