【Objective】Net primary productivity (NPP) of vegetation is an important part of the land surface carbon cycle and is closely related to the processes of carbon recycling and global climate change.NPP of agricultural vegetation represents capacity of the agroecosystemfixing CO₂ from the atmosphere via photosynthesis, and determines how much organic carbonthe agricultural soil can sequestrate. Agricultural soil is a huge carbon(C) pool. An accurate estimation of how much carbon can be turned into organic matter may help better understand the mechanism of carbon recycling in farmland soil, predict which way carbon tends to go in recycling and manage carbon recycling in farmland soil. Chinais a country vast in territory, changeable in climate, complex in type of regions, and diverse in agricultural pattern, making the farmland ecosystems, one of the sectors the most sensitive to global climate change. Size and variation of the agricultural carbon pool is very important to both the world’s food safety and global carbon balance. It is, therefore, of important significance to understanding of the role of China in global carbon recycling and prediction of future trend of the global climate change, to accurately estimate NPP of the farmland ecosystem of China, analyze its spatio-temporal variation rules and explore for its affecting factors【Method】In this study, based on the annual net primary productivity (NPP) data cited from the MOD17A3 dataset, characteristics of the spatial-temporal variation of NPP of the farmland in China and impacts of climatic factors on farmland NPP were analyzed quantitatively with the single factor linear regression trendlinemethod and correlation coefficient method. 【Result】Results show that during the years from 2001 to 2010, the annual NPPs averaged to be C4.12Mg hm^-2a^-1, ranging from 0.21to 17.24 Mg hm^-2a^-1.Within this period of time, annual NPP rose first and then declined, and within the territory of China, the Gansu-Xinjiang Region, the Loess Plateau Region, Northeast China, Inner Mongolia, areas alongside the Great Wall and northern part of the Huang-Huai-Hai Region were quite low in NPP, and even lower than 3 Mg hm^-2a^-1, whereas the Sichuan Basin, Shandong Hilly Region, the coastal areas of East China and areas alongside the Middle-Lower Reaches of the Yangtze River, Yunnan, Guizhou and Hainan were quite high, and even going beyond 5 Mg hm^-2a^-1. In about 55% of the pixels NPP displayed a rising trend, especially in the pixels representing the Huang-Huai-Hai Agricultural Region, the Loess Plateau Region, oasis agricultural areas in Xinjiang, and the south part of the agricultural region of the Middle-Lower Reaches of the Yangtze River. But NPP inNortheast China agricultural zones, Sichuan Basin and most part of the agricultural region of the Middle-Lower Reaches of the Yangtze River displayed reversely. In order to assess the impact of climate factors on crop NPP in China, we analyzed relationships between average NPP and mean temperature and precipitation during the years of 2001—2010. It was found that average NPP was significantly related to precipitation in about 22% of the pixels of the farmland of China, and with temperature in about 7% of the pixels, which indicates that the agroecosystem of China is greatly affected by human activities such as tillage and farming pattern, cropping system and field management.【Conclusion】 Farmland NPP of China varied sharply in space. It was relatively low in the north and quite high in the south, but displayed a rising trend in most parts of the country. However, its spatial distribution did not tally with its variation trend. In areas that used to be low in NPP, a rising trend was observed with NPP, and vice versa. The agroecosystem of China was less affected by climatic factors than by human activities. It is, therefore, advisable to pay more attention to quantification of the factors of human activities in future studies on influential factors of the agroecosystem.