Considering to ability of time series methods to modeling and predicting the phenomena related to water, this study is done with the aim of analysis the groundwater level changes of Tasuj basin with time series models. For this purpose, groundwater level data was received in monthly scale from regional water organization in East Azerbaijan province between 1373-1391. Among different models ARIMA (2,0,3) model by having lowest Akaike information were suitable than other models. Therefore decline of groundwater level from the year 1392 to the year 1401 compared to the base year 1373 fitted to (2,0,3) model and groundwater level changes was predicted until year 1401 in software R with obtained model. The results showed assuming continuing of present condition of application in tasuj basin mean of cumulative decline groundwater level in tenth year of forecast than the first year of forecast (1392) would be 7/25 meter. Results of modeling and forecasting could be applied to optimal and sustainable management of groundwater resource in the Tasuj basin. Optimal management and modification the pattern of water consumption is necessary according to the spread of Tasuj watershed and significant trend in reduction of groundwater volume during the prediction year.