By taken Weifang city as a research area, the variation of carbon source/sink and carbon footprint from 2003 to 2012 at parts of farmland ecosystem in Weifang were quantitatively measured on the basis of terrestrial data including planting area, crop yield and agricultural input. The results showed that 1) Total carbon absorption in the farmland ecosystem was worse than that of emission during the year from 2003 to 2012, with a ratio of 1:7.4, and the growth rate of carbon emission intensity reduced from 0.055% to 0.048%, the growth rate of carbon absorption strength, while, increased from 1.18% to 1.98%, which indicated that the farmland system had stronger function of carbon sinks; carbon absorption and carbon emission in the farmland ecosystem increased by 10.69% and 7.02% respectively during the 10 years, and the absorption rate was higher than that of emission; 2) Vegetable, as the main carbon sink, was accounted for more than 73.31% in the total sinks, while, irrigation, as the main carbon source amongst the six kinds of carbon emission approaches, was accounted for 87.32%; 3) Carbon footprint in the farmland ecosystem reduced from 389 900 hectare in 2003 to 387 690 hectare in 2012, with a lower proportion of 1.456% amongst the ecological productive land areas. The average value of ICF was 0.14 hectare per 10 000 RMB, which meant that 0.14 hectare carbon footprint could be produced on the basis of 10 000 RMB output value in the farmland ecosystem.