Abstarct: Continuous droughts and increasing groundwater abstraction rate in Damghan plain is of important factors in causing groundwater level drawdown. So it is necessary to consider management and protection of groundwater resources as the main element in water resource programs. Simulation of Damghan aquifer in steady state and transient modes by GMS7.1 and MODFLOW by finite difference has been undertaken. Damghan plain is about 1174 km2 and is located in south part of Alborz Mountain. Hydrograph survey of this plain show that average annual decrease of groundwater level was 0.53 m and is a no-drill plain. Data of 40 observation wells were compared with model results and parameters with more uncertainly like hydraulic conductivity in steady state mode and storage coefficient in transient mode were optimized. Calibration and validation results show high correlation between simulated results of the model and calculated values. To prediction groundwater level in future, 4 scenarios including drought, continuation of current trends, 1.5 times and 2 times that of average rainfall have been considered. Result show during 2014, April to 2019, March, with natural trend of rain, there will be 2.9 m decrease in groundwater level and baxse on this amount 245 Mm3 of plain water resource will be lost. Also in the drought scenario, 3.13 m drawdown will result in a deficit of 260 Mm3. Land subsidence has affected 15% of Damghan plain and will get worst in the future.