H.264/AVC coder adopts rate-distortion optimization (RDO) using Lagrange multipliers to determine a set of coding parameters in the rate-distortion sense under some coding constraints. Traditional RDO is carried out on frame level without consideration of the video contents. However, as the human visual system (HVS) makes final evaluations on the quality of the video, it is wise to adapt coding algorithm to the sensitivity of the human eyes. In this paper, we propose a novel macroblock (MB)-level RDO scheme based on perceptual features of the coded video. Experiments have been conducted based on the reference coder JM12.2 of H.264/AVC. Simulation results show that the subjective qualities of the decoded frames are improved without compromising PSNR.