There are various types of ecosystems and complex landform in alpine area of southwestern China, which make it very sensitive to global climate change. Quantifying the spatial and temporal variation of terrestrial ecosystem carbon sink in this place requires a detailed understanding of carbon exchange between vegetation, soil, and the atmosphere. A process-based biogeochemical model CEVSA(Carbon Exchange between Vegetation, Soil, and the Atmosphere) was used to estimate temporal and spatial variations of net ecosystem production (NEP) in alpine area of southwestern China from 1954 to 2010. In this study, the set of independent environmental variables to run the model consisted of climate (ten days mean value of temperature, precipitation, relative humidity, cloudiness), atmospheric CO₂ concentration, soil and vegetation types at a spatial resolution of 0.1°. We first ran CEVSA model with average climate data during the period 1954-2010 until an ecological equilibrium was reached, then made dynamic simulations from 1954 to 2010 with transient changes in climate at a time-step of ten days.To achieve the results, various kinds of computer software were applied, such as ANUSPLIN4.1, Arcgis9.3, SPSS18.0, Fortran 90. The results showed: (1)The mean value of NEP was 29.7 g C·m^-2·a^-1 during the period 1954-2010 in alpine area of southwestern China, with higher NEP in the evergreen needle-leaved and evergreen broadleaved tree cover at low altitude and lower NEP in herbaceous cover at high altitude of study area. (2) Annual total NEP ranged from -8.36 to 29.4 Tg C/a with a mean value of 15.4 Tg C/a. NEP showed a statistically significant decreasing trend with a reduction rate of 0.187 Tg C/a (P<0.05) during the period 1954-2010 and the significant decreasing area of NEP accounted for 35.2% (P<0.05). The decreasing trend was highly significant in herbaceous cover(-0.526 g C·m^-2·a^-2, P<0.01) and evergreen needle-leaved tree cover (-0.691 g C·m^-2·a^-2, P<0.01). (3)Annual total NEP was significantly negatively correlated with annual mean temperature (AMT) (r=-0.454, P<0.01) and positively correlated with annual total precipitation (ATP)(r=0.708, P<0.01). The negative correlation (P<0.05) of annual NEP and AMT existed in 60.3% of the study region while the positive correlation (P<0.05) of annual NEP with ATP existed in 52.1% of the study region, respectively. Herbaceous cover and evergreen needle-leaved tree cover as the two main vegetation types in study area were both correlated negatively with AMT(r=-0.603, P<0.01; r=-0.485, P<0.01) and positively with ATP(r=0.554, P<0.01; r=0.749, P<0.01), reaching an extremely remarkable level. (4)Alpine area of southwestern China acted as a carbon sink, however, a small fraction of terrestrial ecosystems here shifted from carbon sinks into carbon sources in recent 20 years, for that the NPP (net primary production) growth rate was less than that of the soil HR (heterotrophic respiration).These estimates indicate that the carbon sequestration capacity in alpine area of southwestern China was weakened by the ongoing climate change.