The tropospheric sulfate radiative forcing has been calculated using an interactive chemistry scheme in LMD-GCM. To estimate the radiative forcing of sulfate aerosol on climate, a consistent interaction between atmospheric circulation and radiation computation has been allowed in LMD-GCM. The model results indicate that the change in the sulfate aerosols number concentration is negatively correlated to the indirect radiative forcing. The model simulated annual mean direct radiative forcing ranges from -0.1 to -1.2 W m -2, and indirect forcing ranges from -0.4 to -1.6 W m -2. The global annual mean direct effect estimated by the model is -0.48 W m -2, and that of indirect is -0.68 W m -2.