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Aiming at the unclear effect of climate change and planting structure adjustment on agricultural production in Huang-Huai-Hai region, based on denitrification decomposition model (DNDC), the effect of climate and planting structure change on agricultural greenhouse gas (CO2, CH4 and N2O) emission and irrigation water demand in the Huang-Huai-Hai area was assessed by scenario analysis. The results showed that from 1995 to 2015, the climate in the study area developed towards the direction of warm and humid, in which the average annual maximum temperature did not change significantly, the average annual minimum temperature increased by 0.7℃, and the annual precipitation increased by 46.5mm.In 1995, the planting area of maize, wheat and rice was about 7.9×106 hm2, 1.4×107hm2 and 2.9×106hm2, respectively. In 2015, the planting area of three crops was increased, while the planting proportion of rice and wheat was decreased. Under the influence of climate change, agricultural greenhouse gas emissions were increased and irrigation water demand was decreased slightly in the Huang-Huai-Hai region. Compared with that in 1995, the emission intensity of CO2, CH4 and N2O was increased by 4.7%, 0.8% and 26.2% respectively to 3730.5kg/hm2, 443.2kg/hm2 and 5.9kg/hm2 in 2015, and the irrigation water demand was decreased to 499.3mm with decrease of 6.6%. The adjustment of planting structure changed greenhouse gas emissions and irrigation water demand. The evolution of planting structure in the Huang-Huai-Hai region increased the total emissions of CO2, CH4 and N 2.O to 9.9×107t, 1.4×106t and 1.3×105t, which was increased by 13.8%, 8.6% and 13.3%, respectively. Meanwhile, in some areas, the irrigation water demand was increased with the increase of corn planting proportion as a high waterconsuming crop. The research results can provide theoretical basis for the formulation of future agricultural water saving and emission reduction policies in the Huang-Huai-Hai region.