The natural wetland landscape was seriously degraded in thirty years (1975-2004), because of the high-intensity agricultural exploitation in Sanjiang Plain. It is very important to conduct landscape assessment for wetland preservation and restoration in the region in terms of the various pressures to, and the present state and change of the wetland. By choosing Landsat TM remote sensing data of the years 1975, 1989 and 2004, the landscape change of Jiansanjiang region of Heilongjiang Province was analyzed on the basis of Presure-State-Response ecological assessment framework. The results showed that, (1) From 1975 to 2004, the natural wetland was greatly decreased while farmland obviously increased, and landscape diversity and fragmentation were remarkably increased; Agricultural exploitation was the main pressure the wetland faced during the period, where wet meadow and swamp were the main targets of the exploitation. (2) The agricultural exploitation in 1975-1989 was much higher than that in 1989-2004. From 1975 to 1989, the areas of farmland and drainage ditch were abruptly increased while that of wetland was greatly decreased, that is, the wetland was mainly converted into farmland through the discharge of drainage ditch system, which led to the decline of ecological and environmental quality, especially the frequently happened flooding, in the region. However, from 1989 to 2004, wetland preservation was recognized important, the exploitation on natural wetland was limited and the drainage ditch was slightly increased, moreover farmland was partially converted into paddy field so that to preventing flooding. Meanwhile, some wetland nature reserves were established during the period alongside the establishing of some wetland conservation regulations, the wetland landscape was then preserved to a certain extent. (3) The problems that Sanjiang Plain wetland landscape facing are still serious at present, especially the shortage of regional water resources and the declining of underground water level because of the existence of drainage ditch system and the conversion of farmland to paddy field, which will continuously threaten the survival of current wetlands, therefore it is urgent to synthetically manage regional water resources on the basis of drainage ditch system.