Abstract: The wetlands in Sanjiang Plain are significant for regional ecological security owing to their important ecological functions such as conserving water source, keeping biodiversity, and so on. On the other hand, Sanjiang Plain plays a very important role in ensuring the Chinese food security with its suitable climate and allocation of water and land resources. But, during the course of constructing Chinese commodity grain base, the expansion of the farmland led to the shrink of wetlands. Human activities changed the pattern of land use in Sanjiang Plain and negatively affected on regional ecology and led to the declination of the regional ecological quality, even menace the ecological security. To lessen those contradictions require the coordinated development of arable land and wetlands. In order to seek rational proportion between the arable land and wetland, this paper analyzes the relationship between arable land and wetland in Sanjiang Plain, and constructs a set of index system for coordinated development between both. With the help of the exponential evaluation model, the coordinated development level of arable land and wetland in Sanjiang Reserve is evaluated. The results show that the coordinated development level between the arable land production and the wetland environment is better from 1954 to 2000.The topmost point of coordinated development level was attained in 1995, while that of comprehensive development level in 2000. However the coordinated index and comprehensive index take on a great degressive trend appeared in 2000, which is mainly resulted from the decline of wetland exploitation carrying capacity, particularly the reduce of wetland value has threaten the sustainable development of Saijiang Reserve. From 1995 to 2000 when the coordinated index and comprehensive index attained the topmost point, the area of arable land was about 26, 000 hm² and the wetland was 35, 000 hm² in Saijiang Reserve, which can be taken as a reference standard when defining the level of wetland restoration.