Researching the carbon emissions trend evolution rule and carbon reduction potential in regional crop fertilizer application is of great significance for formulating reasonable agricultural carbon reduction policy．Based on actual outputs and fertilizer inputs and types for three main grain crops in China we used the carbon emissions coefficient method to estimate and analyze the space-time evolution of carbon efficiency and carbon emissions reduction potential in Chinese grain crop fertilizer consumption from 2005 to 2013. We found that the amount of carbon emissions per unit product in the Jiangsu,Anhui,Ningxia,Gansu and Shanxi maize-growing area,Hubei,Shanxi and Ningxia wheat planting and Liaoning,Shandong,Jiangsu,Zhejiang,Shanxi and Hunan rice-growing area decreased significantly. Carbon emissions per unit product in the Heilongjiang,Jilin and Xinjiang maize-growing area,Yunnan and Henan wheat-growing area and Jilin,Guangxi and Yunnan rice-growing area increased. Compared with soil testing and formula fertilization,carbon emissions per unit product were high in 2013 in the Jiangsu,Shanxi,Hubei,Guizhou,Guangxi and Yunnan maize-growing area,Shanxi,Neimenggu,Shanxi,Gansu,Ningxia,Xinjiang,Hebei,Sichuan,Yunnan and Jiangsu wheat-growing area,and Hunan,Jiangsu,Hainan,Anhui,Yunnan,Guangdong and Guangxi rice-growing area. The carbon emission reduction potential of the maize-growing in China is 5.74 million t CE and focuses on Heilongjiang,Liaoning,Jilin,Shandong,Neimenggu,Shanxi,Yunnan,Guizhou and Guangxi. The carbon emission reduction potential of the wheat-growing in China is 4.75 million t CE,focusing on Hebei,Jiangsu,Shandong and Henan. The carbon emission reduction potential of rice-growing in China is 2.06 million t CE,focusing on Hunan,Guangdong,Guangxi,Jiangsu and Jiangxi. Combined with field investigation and analysis we propose potential carbon emission reductions in food crop cultivation through policy incentives and market operations in order to improve the effect of soil testing and fertilizer application technology.