The calligraphy in Song dynasty had the trend of "Shang Yi" under the guidance of Ouyang Xiu, Cai Xiang and Su Shi. Cai Xiang's calligraphy and theory, as one part of the traditional Chinese culture, have played an important role in linking the past and the future in Chinese calligraphy. However, there were opposite voices in the academic circles during a long time, and furthermore, Cai Jing, instead of Cai Xiang, is one of "four great calligraphers in Song dynasty", which is a fallacy in today's perspective. Now with the help of historical records, this paper gives overall review and evaluation on his works.