Abstract: A net primary productivity (NPP) model of agricultural vegetation was presented based on the ecophysiological feature of plants and climatic factors: NPP=exp(rRn(r2+Rn2+rRn)/(Rn+r)(Rn2+r2)•(0.0015RDI+0.0013) This model was used to simulate the NPP of agricultural vegetation according to the comparison between the observed agricultural NPP data from 27 provinces and cities and the simulated data, which were in good agreement. The sensitivity study of agricultural vegetation was also done with the new NPP model in China. The results showed that the crop productivity would increase by 0.44 % to 12. 88 % in China when the temperature inereased by 2 ℃ and precipitation unchanged or increased by 20%. It would increase by 5.46% to 12.88% in moist area when precipitation change and inereased by 4.15% to 10.92% in arid and semiarid areas when precipitation inereased by 20%; and it would increase by 1.48 % to 14.63 % in moist area, decrease by 0.44 % to 6.01% in arid and semiarid areas especially in arid area when the temperature increased by 2 ℃ and precipitation decreased by 20%. This indicated that water was a key factor to agrieuhural vegetation. The new NPP model would help us to understand and forecast agricultural development, to organize agricultural activity effectively, to make good use of agricultural resources, and to increase lands capacity.

Key words: Agricuhure, Net primary productivity model, Global change