Abstract: High quality NDVI time series data are reconstructed after removing the noise caused by cloud and water vapor using Harmonic Analysis of Time Series (HANTS) method based on the GF-1 wide field view (WFV) data of crop growth period in 2018.The characteristics of main crops during key growth periods are analyzed with the ground sampling data, and the crop classification model is constructed to monitor the crop planting structure in Yellow River irrigation area of Ningxia.The results show that the overall classification accuracy of the main crops is 86.5%, and the Kappa coefficient is 0.77.The classification accuracy of spring wheat, maize and paddy rice are 76.9%, 88.8% and 85.5%, respectively.The planting area is 45451.0 hm², 214703.1 hm² and 81472.6 hm², respectively, accounting for 9.0%, 42.3% and 16.1% of the crop area in the Yellow River irrigation area.Based on GF-1/WFV multi-temporal data, the decision tree classification method can be used to obtain highaccuracy main crop information so as to provide reference for the study of main crop information extraction.Therefore, the method is of application value for operational monitoring.