The objective of joint rate control is to dynamically distribute the channel capacity among video sequences according to their respective complexities, thus a more uniform picture quality and a more efficient utilization of channel capacity are achieved. Most existing approaches are based on MPEG2 coding platform. This paper presents a novel joint rate control scheme for multiple video sequences coding based on H.264 standard. A novel complexity measure that adapts to the characteristics of H.264 video coding is proposed. Experimental results show that the proposed scheme maintains a good balance in picture quality among the sequences as well as within a sequence.