One of the important challenges for water resource researchers is Integrated Water Resource Management (IWRM). Indeed, IWRM is conjunct surface- ground water operation for sustainable water use and increase of available water. Hence, normative planning in this area requires knowledge of surface- ground water interaction process, estimation of effective parameters and factors affecting inside the system. So the basic objective in current study is surface- ground water interaction simulation in terms of dynamic coupling between ground and surface water in Dez plain (consist of five under plain: Loor, Dimcheh, Dez-Gharbi, Dez-Sharghi, Sabili). When properly linked, data and results flow back and forth between WEAP and MODFLOW for each calculation time step and for any feedback WEAP value for groundwater infiltration and abstraction, river stage and surface runoff will be sent to MODFLOW as inputs for its calculations, and MODFLOW results for (head), lateral flow between aquifers, and etc. come back to WEAP as inputs for its calculations. Results illustrate that in northern to central parts of the plain, aquifer recharge by Dez and Karkheh rivers. Most of the times these rivers in central to southern parts of the plain act as drainage (such as other rivers in Dez plain). Simulation results illustrate that due to operation of deep wells as the only available water source in Loor, Maximum drawdown was done in this area. However water table increased in Dimcheh. Generally in areas of Dez plain, where focuses on sustainable conjunctive use of surface and ground waters, water demands will be coverage more than 80% by surface water and 20% by ground water.