In this study, the impact of dams on land use changes and water level of the lake Urmia in a 40-year period were studied.For this purpose, the digital data for 1354, 1368, 1385 and 1393was prepared using MSS, TM and OLI sensors of Landsat and a total of 38 satellite image was used for the analysis and classification. Then, desired classes including irrigated agriculture, water, pasture, man-made, salt marsh and no vegetation were separated. Results showed that generally, in this area during the study period the area of water and pasture cover decreased, while the areas of irrigated agriculture, saltmarsh, no vegetation area and man-made classes have increased. Moreover, although the area of water class has experienced the most significant decline, the irrigated agriculture has enjoyed the highest grows rate. The results of the system analysis showed that considering parameters such as population growth, precipitation level, input water flow (of the lake), during the first interval the impact of the dams were limited while the natural parameters have a high impact on the water level of the Lake. But in the second and especially third periods the severity of the impact of the dams on the land use changes and reducing the water level of the lake has been more evident.