[Objective]To explore the sources and quantification of soil moisture in the crop root zone in the Huaibei Plain from 1990 to 2022, and to provide scientific guidance for crop irrigation management and water resource utilization. [Methods] This article first combines Pearson correlation analysis and multiple regression to calculate the contribution of precipitation and groundwate r in soil water in the crop root zone, and then uses multiple linear regression and long short-term memory network (LSTM) models to quantitatively simulate the soil water in the root zone. [Results] ① For summer corn, in the 0-10 cm soil layer, except for the 55% contribution of precipitation during the seedling-jointing period, the contribution of groundwater in other stages can reach 61%-68%; in the soil layer below 10cm, the soil water in the root zone mainly comes from the soil water in the adjacent upper layer, accounting for more than 74%. In the later stage, the root system gradually grows to 100cm, especially in the 40-80cm soil layer, the contribution of groundwater to soil water increases significantly, accounting for 9%-22%. ② For winter wheat, in the 0-10 cm soil layer, except for the sowing-seedling period and the greening-jointing period, the contribution of groundwater in other stages can reach 54%-73%; in the soil layer below 10cm, the soil water in the root zone mainly comes from the soil water in the adjacent upper layer, accounting for more than 63%. However, in the 40-80cm soil layer, the contribution of groundwater and precipitation has increased relatively.③The LSTM model is more stable and accurate than multiple linear regression in quantitatively simulating soil water. The model evaluation index can reach R2>0.6 and MSE<10, which can better reflect the dynamic changes of soil moisture. The application of the above simulation results at other stations in the Huaibei Plain further verified the feasibility of the model. [Conclusion] The main source of soil water in the 0-10cm layer for summer corn is groundwater, and the main source of soil water in the 0-10cm layer for winter wheat is precipitation; the main source of soil water below 10cm is soil water in the adjacent upper layer (including precipitation, irrigation water, etc.).A quantitative simulation was performed based on the sources of soil water in the root zone at different growth stages. It is helpful to dynamically adjust the irrigation plan through the changing trend of soil moisture in the root zone of the crop. To optimize irrigation management and improve water resource utilization efficiency.