Although there are many comments on Zhang Ruitu's calligraphy, few people point out its origin. Judging from his small seal script works handed down from generation to generation, such as Book Review of Shengshou, Infinite Poem Volume, etc., the structure is flat, the strokes are multi-faceted, the thickness of strokes is strongly contrasted, and they are strange and vigorous, with the charm of Zhong You's opening method; However, in his cursive scripts, such as Poems in Chenzhou Road, Five Wonders of Poems Axis, and Li Bai Sitting Alone in Jingting Mountain, it is difficult to know the number of ways for disciples to come and go. If we weaken the strong sidelights and sharp turns in these works, everything will be suddenly enlightened, and it is easy to find that the laws of knot and strength still come from Zhong You and Erwang, especially Erwang. Zhang deleted all the round characters in the calligraphy of the two kings and changed them into round characters; In the use of pens, he exaggerated the habit of revealing the front in calligraphy; In composition, we emphasize the horizontal direction, tighten the word spacing, and use the airtight horizontal painting arrangement with sparse line spacing to produce a strong visual impact, thus creating a critical momentum. People who don't know the true face of Lushan Mountain in later generations think that "(Zhang Ruitu's) calligraphy is a must, and he has found another way outside" (Qin's "On Painting with Same Yin").
Calligraphy, based on Zhong and Wang, finally became independent after several times, which was closely related to the ideological trend of emphasizing personality liberation in the late Ming Dynasty. His calligraphy inherited and rebelled against tradition with its unique brushwork, composition, special rhythm and charm, which inspired many artists to actively pursue their own values and had a direct impact on Huang Daozhou, Ni, Wang Duo, Fu Shan and others at that time.