To adapt the diversification of network and terminal devices better,an optimization scheme of scalable video coding was proposed with Motional Region of Interest (MROI) based on H.264.The motion information and coding mode in base layer were used to determine the MROI,and then the MROI was enhanced as one slice by scalable coding.Experimental results show that the proposed scheme can greatly decrease coding complexity and make the MROI information have a higher probability to be included in the truncated bit stream.Therefore,the scheme improves the reconstructed quality of the potential MROI and subjective quality of the whole image.