Constraining the variation of G by cosmic microwave background anisotropies

We use the Cosmic Microwave Background Anisotropies (CMBA) power spectra to constrain the cosmological variation of gravitational constant G. It is found that the sensitivity of CMBA to the variation of G is enhanced when G is required to converge to its present value. The variations of G from the CMB decoupling epoch z similar to 1000 to the present time are modeled by a step function and a linear function of scale factor a respectively, and the corresponding 95% confidence intervals for G/G(0) are [0.95, 1.05] and [0.89, 1.13], G(0) being the present value. The CMBA constraint is unique in the sense that it entails the range of redshift from z approximate to 1000 to 0.