The Urmia Lake has distinctive nature, hydrodynamic and environmental properties that single out that from the other lakes in the world. Construction of Shahid Kalantari causeway can cause significant effects on natural regime of the lake. It may affect on environmental biology, hydraulic, water circulation regime and … . This paper deals with hydrodynamics of the lake. Two-dimensional surface simulation has been done with MIKE21 program. Flow regime and relative effects of parameters influencing that has been investigated. Results from this model when simulating normal condition, has been found to present a good correlation with field data as level fluctuations and velocity range. For that it seems that using 2D model for hydrodynamic is suitable but calibration with field data is needed for its approval. This model shows that the wind input as the main environmental parameter influencing the flow regime in the Lake and for that it is important object for defining design parameters.