This study presents a cost-effective annual cropland mapping framework for China, developed using Landsat satellite imagery, automated training sample generation, machine learning, and change detection techniques. The framework, implemented on Google Earth Engine, generates a novel 30 m spatial resolution dataset (CACD) of China's annual cropland from 1986 to 2021. The pixel-wise $F_1$ scores for annual maps and change maps of CACD were 0.79 ± 0.02 and 0.81, respectively, demonstrating high accuracy and robustness. The dataset reveals that China's total cropland area expanded by 30,300 km² (1.79%) from 1986 to 2021, with an increase before 2002 followed by a decline until 2015 and a slight recovery afterward. Cropland expansion was concentrated in the northwest, while eastern, central, and southern regions experienced significant cropland loss. Additionally, 419,342 km² (17.57%) of croplands were abandoned at least once during the study period. The consistent, high-resolution data provided by CACD support sustainable agricultural use and food production in various research applications. The full archive of CACD is freely available at https://doi.org/10.5281/zenodo.7936885.This study presents a cost-effective annual cropland mapping framework for China, developed using Landsat satellite imagery, automated training sample generation, machine learning, and change detection techniques. The framework, implemented on Google Earth Engine, generates a novel 30 m spatial resolution dataset (CACD) of China's annual cropland from 1986 to 2021. The pixel-wise $F_1$ scores for annual maps and change maps of CACD were 0.79 ± 0.02 and 0.81, respectively, demonstrating high accuracy and robustness. The dataset reveals that China's total cropland area expanded by 30,300 km² (1.79%) from 1986 to 2021, with an increase before 2002 followed by a decline until 2015 and a slight recovery afterward. Cropland expansion was concentrated in the northwest, while eastern, central, and southern regions experienced significant cropland loss. Additionally, 419,342 km² (17.57%) of croplands were abandoned at least once during the study period. The consistent, high-resolution data provided by CACD support sustainable agricultural use and food production in various research applications. The full archive of CACD is freely available at https://doi.org/10.5281/zenodo.7936885.