Cropland is the basis of grain production. In recent decades, the spatial pattern of cropland in China has changed significantly, which has caused some impact on grain production. Based on land cover data of 1990, 2000, and 2010, this study explored changes in the spatial pattern of cropland, and constructed a database with a spatial resolution of 1 km based on county-level agricultural statistics and soil organic matter data, which is the representative of crop productivity. The results show that: during the period from 1990 to 2010, drastic reclamation happened in Northeast and Northwest China while the cropland acreage decreased in Huang-Huai-Hai Plain; the main source of new cropland during the study period was grassland (46.9%), and the lost cropland was mainly converted to forest land (36.6%) in the first ten years and then to construction land (53.0%) in the following ten years; the changes in the spatial pattern of cropland have caused a decrease of 2.0% in the average crop productivity, and during this period, the construction land mostly occupied high-quality cropland, while the newly reclaimed cropland had lower crop productivity.