Abstract: Satellite remote sensing has significant advantages for identifying irrigation information, including irrigated area and irrigation frequency, because of its rapid and wide-area observation capability. However, the spatial and temporal resolution of a single remote sensing data source is often insufficient to meet the demand for high-accuracy dynamic identification of irrigation information at the regional scale. Taking the Guanzhong region as the study area, this study developed a remote sensing method for irrigation information identification based on drought index analysis and spatiotemporal fusion. The temperature vegetation dryness index (TVDI) was selected as the identification indicator through correlation analysis between drought indices and soil moisture, and elevation correction together with fusion-strategy optimization was introduced to improve the capability of TVDI to characterize soil moisture and to enhance its spatiotemporal fusion accuracy under complex terrain conditions. Subsequently, the enhanced spatial and temporal adaptive reflectance fusion model (ESTARFM) was used to fuse high-spatial-resolution Landsat imagery and high-temporal-resolution MODIS data to generate a high-spatiotemporal-resolution TVDI time series, and spring irrigation information in the Guanzhong region in 2024 was identified using a threshold-based method. The results showed that the elevation-corrected TVDI was highly correlated with soil moisture during the spring crop growth period, with the maximum correlation coefficient reaching -0.77. In the fusion of TVDI, the strategy of first fusing the normalized difference vegetation index (NDVI) and land surface temperature (LST) and then calculating TVDI achieved higher accuracy than the strategy of first calculating TVDI and then performing fusion, with R² = 0.76 and RMSE = 0.07 for the former, and R² = 0.44 and RMSE = 0.13 for the latter. Validation at the irrigation-district scale showed that the overall accuracy of irrigated area identification in the Donglei Phase II Irrigation District was 90.8%, with a Kappa coefficient of 0.80, while the mean accuracies for accumulated irrigated area and actual irrigated area in the three validation irrigation districts were 87.1% and 87.5%, respectively. Regional identification results indicated that spring irrigation in the Guanzhong region was mainly concentrated from March to April, with irrigation frequency predominantly ranging from one to two times, and irrigated areas mainly distributed in the Weihe Plain. The results can provide a methodological reference for regional-scale irrigation information identification under complex terrain conditions.