One of the most important factors affecting groundwater status is the crop pattern that its optimization can have positive effects such as reducing pressure on water resources and increasing farmers' incomes. Since no study on Kermanshah plain aquifer modeling and determination of optimum crop pattern using system dynamics approach has been done so far, a research was required for the study area about this subject. For this purpose, aquifer modeling of Kermanshah plain was performed in GMS 7.1 software using MODFLOW model for the first time. In order to be more precise in the calculation of management scenarios, the factors affecting the status of water resources were defined as a dynamic model in Vensim PRO x32 software. Then, four scenarios about water supply resources of the agricultural sector were applied over the dynamic model. The results obtained from the dynamic model were applied to the groundwater model and the status of representative hydrograph of aquifer was determined by applying each scenario. In order to predict climate parameters values to investigate the aquifer status in the future, stochastic simulation of time series was used. In this research, crop pattern optimization of Kermanshah plain was performed by the existing optimization tool in Vensim PRO x32 software using multi objective mathematical programming approach by Powell method in three different scenarios for the first time. The values ??of coefficient of determination, maximum error and root mean square error for the groundwater model were 0.93, ±1 m and 0.64, respectively, indicating acceptable accuracy of the model for simulating aquifer status. Based on the obtained results of the groundwater model, the hydraulic conductivity in the aquifer of ??Kermanshah plain varied from 0.1 to 30 m/day and specific yield varied from 0.02 to 0.4. The values ??of coefficient of determination and error percentage for the dynamic model were 0.98 and less than ±2%, respectively, indicating the validity of the model for simulating the real system. The prevailing time series model for monthly rainfall, evaporation, potential evapotrairation and river discharge data was PARMA (1,0) model. Evaluation of accuracy and efficiency of time series models using two statistics root mean square error and Nash-Sutcliffe showed that the selected time series models were acceptable. The values ??of coefficient of determination and root mean square error in the accuracy assessment of groundwater, dynamic and time series models in predicting future water table level were 0.82 and 0.83, respectively, indicating acceptable accuracy of the models in predicting groundwater status in the future. The results showed that if the water requirement of the agricultural sector is supplied only by the aquifer, the groundwater level will decrease by an average of 0.9 m from the beginning to end of the 10-year period (2016-2026). Applying this scenario resulted in the lowest groundwater level and the lowest percentage of water requirement supply for crop pattern plants compared to other scenarios defined in this study. If the water requirement of the agricultural sector are supplied by a combination of effective rainfall, dam, aquifer and refined sewage, groundwater level will increase by an average of 2.1 m from the beginning to the end of the 10-year period. Applying this scenario resulted in the highest groundwater level and the highest percentage of water requirement supply for crop pattern plants compared to other scenarios defined in this study. The results showed that if it is possible to change the crop coefficients of all plants in crop pattern optimization, the percentage of cultivation related to wheat, grain and forage maize, barley, tomato, clover, and onion decreased and the greatest increase of cultivation area allocated to sour cherry, quince, olive, pear, saffron, cherry, rose, greenhouse, plum, and medicinal plants, respectively. If the area covered by wheat is not changed, the cultivation percentages related to grain and forage maize, barley, tomato, clover, onion, faba bean, and apple decreased and the cultivation percentages of other plants increased. Also, if the area covered by wheat and gardens are not changed, the cultivation percentage of crops including grain and forage maize, barley, and clover decreased and the cultivation percentage of other plants increased. The ratio net benefit-to-extracted water from the aquifer in the optimization scenarios was more than the current crop pattern and indicated that the optimum crop patterns were preferred over the current crop pattern. Key Words Aquifer modeling, System dynamics modeling, Time series modeling, Crop pattern optimization, GMS 7.1 software, Vensim PRO x32 software.