Abstract: In this paper, the impact of total solar irradiance (i.e., solar constant) variation upon global radiative forcing and climate change in winter (December - February) is investigated by using a global atmospheric general circulation model (IAP AGCM4.0). Two sets of numerical experiments are designed, with one using the default solar constant (1367W·m^-2) and the other adopting the latest value (1361W·m^-2). Comparisons of the model results from both experiments demonstrate that with the reduction of solar constant: (1) Incoming solar radiation decreases 1.54W·m^-2globally and 2.15W·m^-2over areas of the mid- and high-latitudes in the Southern Hemisphere. Corresponding to less total cloud cover, net solar radiation at the top of the atmosphere and the surface increases in regions such as North America, West Siberia, Middle East, and Eastern Australia; (2) Surface temperature decreases 0.05℃ globally and more than 2℃ over Eurasia, while it increases about 0.5℃ over Eastern Australia. In other regions such as Southern North-America, Southern South-America, Eastern and Southern Africa, and Western Australia, surface temperature becomes colder. Over regions including Northern North-America, Northern South-America, and Western Africa, surface temperature becomes warmer. (3) Precipitation exhibits negligible variations when averaged globally, which only drops by 0.003 mm·d^-1. Owing to the combined effects of decreased surface evapotranspiration, reduced surface humidity, and weakened Australian summer monsoon, precipitation over Eastern Australia is on average reduced by about 0.6 mm·d^-1.