Rate control scheme plays a vital role in the circumstances of region-of-interest (ROI) based video coding, aiming to allocate a higher bit rate to the ROI while setting a relative lower bit rate ratio in non-ROI to maintain the total bit rate close to the assigned target value. Among various rate control models, the R-Lambda based rate control model outperforming other models. Unfortunately, the R-Lambda model fails to reflect the content of video, and the consequence is a downgraded achievement of the rate control. This paper is proposed to design a new rate control scheme based on the saliency map, aiming at extending saliency based rate control algorithm to both frame level and coding tree unit (CTU) level. Experimental results indicate that the proposed bit allocation structure provides an improvement in the region of interest by employing the peak signal-to-noise ratio (PSNR) quality and the subjective assessment.