Based on data of the precipitation, temperature and cloud cover of 25 stations in Hangzhou Bay region and the global annual volume fraction of CO₂ from 1971 to 2006, the annual vegetation net primary productivity (ANPP) is simulated by the LPJ model (Lund-Potsdam-Jena dynamic global vegetation model).The temporal and spatial characters of the ANPP in the region are analyzed and the driving fa ctors of ANPP are further investigated.Results show that:1) The average increasing rate of ANPP is 1.5243 g·m^-2·a^-2 in the whole region.However, ANPP spatially show different increasing rates fr om 1971 to 2006, with the significant rate in the north of Jiaxing and the east of Shaoxing.2) The multiple linear regression analysis shows that there is a close relationship between cloud cover and ANPP with-0.5175 partial correlation coefficient.However, the correlation between ANPP and temperature (precipitation) is inconspicuous.Response of ANPP to climate change shows a certain geographical distribution for the different hydro-thermal conditions.3) In the whole region around Hangzhou Bay, the average trends caused by decline of temperature, increase of precipitation, reduction of cloud cover and enhancement of volume fraction of CO₂ are -0.0813, -0.0171, 0.7601, and 0.8673 g·m^-2·a^-2, and their attributions to the change of ANPP are -5.18%, -1.09%, 48.38% and 55.21%, respectively.Therefore, the changes of volume fraction of CO₂ and cloud cover play important roles to affect the change of ANPP, however, change of precipitation has little action to the ANNP.