Directly driven ablative Rayleigh–Taylor (R–T) instability of modulated CH targets was studied using the faceon X-ray radiography on the Shen-Guang II device. We obtained temporal evolution images of the R–T instability perturbation. The R–T instability growth factor has been obtained by using the methods of fast Fourier transform and seeking difference of light intensity between the peak and the valley of the targets. Through comparing with the the theoretical simulation, we found that the experimental data had a good agreement with the theoretical simulation results before 1.8 ns, and was lower than the theoretical simulation results after that.