Since the publication of the High Efficient Video Coding (HEVC) as the newest video coding standard, some extension of HEVC has been explored. Intra Block Copy (IntraBC) is one of the most important tools defined in screen coding extension of HEVC. However, the simplex partitioning method used in IntraBC leads to the problem that one CU may contain several irrelevant and complex texts or graphs, which degrades the coding efficiency. In this paper, an improved Intra block copy algorithm is proposed based on character segmentation exclusively for screen videos containing a large number of texts. Experimental results show that the proposed algorithm can provide a Bjøntegaard delta bit rate (BD-rate) reduction of 0.72% with only 3% increase in encoding time and no increase in decoding time compared with the default algorithm in HM-16.7+SCM-5.4.