At present, the collection of Xiang Xue in Tiandulou is framed by Japanese method, which is the representative work of Song Cao's calligraphy returned from overseas. The layout of the whole work is smart and vertical, the pen is solid and heavy, round and full of bones, wrapped in iron, and there is no fancy. In his temporary work, the font is wide, the strokes are heavy and the structure is restrained, which gives us a particularly strong sense of "fat strength". Song Cao's calligraphy is more heroic. Although it has the so-called "fur feeling", his works show more the rugged and heroic spirit of the northern calligraphy style, conquer the audience with momentum, and pursue "ancient", "elegant" and "healthy" aesthetically, which is obviously different from the prevailing styles of Dong and Zhao in the early Qing Dynasty.