To effectively analyze the factors that influence the dynamic change of natural wetland,this paper utilized landscape development intensity index to quantify the impact strength of human activities to nature reserves.The Landsat TM images of eastern Inner Mongolia from 2000 to 2012 were taken as data source,and the classification method that combines object-oriented with decision-tree was applied to obtain the land cover data of each national wetland nature reserve.The dynamic change of natural wetland in nature reserves was analyzed by integrating the methods of dynamic degree and spatial analysis. This study can provide references for research and protection of wetlands.The results show that:during the period of 2000~ 2012,the area of natural wetland including swamp and water body in national wetland nature reserves of eastern Inner Mongolia decreased with time,among which the area of Dalaihu Natural Reserve had suffered the most serious decline;the reduced natural wetland was mainly transformed into bare land and grassland,accounting for 50.57% and 46.22% of total natural wetland convention area,respectively;from 2000 to 2012,Tumuji and Dalaihu Nature Reserves had experienced the most obvious increase of influence intensity of human activities;the decrease of natural wetland area was attributed to the dual effects of climate change and human activities,the former is the internal factor,and the latter is the external factor.