Based on the temperature and precipitation data got from 52 meteorological stations within and around the Weihe River Basin between 1959 and 2010, Net primary productivity (NPP) was calculated using Zhou Guang-sheng and Zhang Xin-shi Model. The spatial and temporal variation of temperature, precipitation, humid index, NPP and their relations were analyzed by using linear regression, correlation analysis and Spline spatial interpolation method. The possible response of NPP to the variation of temperature and precipitation in the future was discussed. The main results are as follows: (1) Climate became warmer with a trend rate of 0.4 ℃/10a, and the increase in the northern part was larger than in the southern part, eastern part was larger than western part. Precipitation was decreasing with a trend rate of -20.1 mm/10a, which was larger in southern part than in northern part; (2) The humid index was decreasing with a rate of -0.02/10a, but Guanzhong area presented a slight tendency of becoming wetter; (3) The NPP was large in Qin Mountain, Guanzhong area. NPP of the whole basin was decreasing while a few stations presented a slight increasing tendency. The trend rate of NPP in southern part was bigger than in northern part, which was in accordance with the distribution character of precipitation. (4) NPP correlated positively with humid index and precipitation, while correlated negatively with potential evapotranspiration, sunshine duration and temperature. Temperature had limited impact on accumulation of NPP, precipitation was the main limit factor; (5) The result of simulation demonstrated that under the scenario of temperature and precipitation increasing at the same time NPP would increased by approximately 15% or 10%. Under the scenario of annual precipitation decreasing by 20%, NPP would also decrease, only a few stations increase insignificantly.