Combined with SPSS statistical analysis software, time series analysis theory was applied to simulate and forecast the dynamic change of groundwater level in Helan. The result shows that the annual variation of groundwater level has no significant ascending or descending trend which means a little change of the condition of recharge, run-off and discharge of groundwater in the study area. Affected by irrigation and rainfall, the groundwater level mainly shows period variation of one year in the study area. It applied time series analysis method to forecast the dynamic change of groundwater level so as to know the trend and period of groundwater level.The method has simple computation and a high accuracy in short period, and needs less data. But the data should be continually and promptly updated in practical application. Its application is limited in certain degree and needs to be improved because of ignoring the hydraulic mechanism of groundwater flow system and the abrupt change of the future.