Abstract: The CO2 obsorption from crops have been estimated on the basis of crops production data (FAO 1992).It is about 550 million t/aC in China and 2890 million t/aC in the world.And making use of photosynthetic experimental data for wheat,corn and soybean in all growing seasons to calculate absorption of C directly.It shows that there is 2.6% error between estimation and calculation.Thereby according to experimental resups of crop response to doubling CO2,crops absorb CO2 will increase 21%-26% under doulbing CO2 concentration condition(700ppm compared with 350ppm),that is,the total CO2 absorption from crops will be 660-690 million t/aC in China and 3410-3620 million t/a C in global world.Additionally,this study presents crops absorb C per planting area is 4.2t/(hm2·a) in China.It is 25.4% more than mean level of the world (3.2t/hm2·a),and crop species C4,is more than C3 generally.