Abstract: In this paper, an algorithm of real-time video character locating based on ROI motion detection is presented to solve the low efficiency problem of character locating in video shot by mobile devices.Considering the video images' features of discontinuity and similarity, this method uses regional motion detection to track the position of equipment and get the region of interesting (ROI) from the result of first frame character detection,then calculate the changes of ROI state (marked with ⊿) of adjacent frames.Only when ⊿ is greater than the threshold value,the method relocates the frame.The others will use the location result of last frame.The character locating algorithm mainly uses the combination of mathematical morphology and connected region analysis.The experimental results indicate that the proposed method can effectively improve character locating speed in mobile platform.