Multiple cropping system is essential to Chinese agriculture, which can significantly increase grain yield and promote agricultural economic development. Multiple Cropping Index is fluctuating year by year due to the changing natural conditions and rural social status, so, it is very important to get the change information in time for food security assessment and scientific decision on agricultural development and planning. The discussions about food security in recent years mostly focused on the peril caused by decreased cropland area, whereas neglected the loss of actual sown area due to Multiple Cropping Index decrease. As the only data source for sown area or MCI change assessment on national scale, statistical data not only is time-lagged and poor in creditability but also lack spatially explicit description. In this study, we extract multiple cropping information from 8 km 10-day composite AVHRR/NDVI time series images according to the phenological metrics and farmland practice temporal features, and then analyze MCI changes from the 1980s to the 1990s. This study shows that China's MCI increase as a whole, but 15% of cropland area has suffered MCI decrease that is mainly distributed in the Zhujiang River Delta in South China, the middle and lower reaches of the Yangtze River, hilly area of Sichuan Basin and Shandong hilly area of Huang-Huai-Hai region. In the Sichuan Basin and the Huang-Huai-Hai region, the MCI decreased croplands are mostly distributed in hilly area, while MCI of cropland in plain area increase or keep stable.