He spent the remainder of the war writing articles on paleography and textual history, and was appointed to the rank of associate research fellow.

Despite attempts at support from the department's administrator, he was fired during the late 1950s Anti-Rightist Campaign, and worked for several years as an editor at the Zhonghua Book Company.

In 1966, he was appointed to a senior research fellowship, but was sent the same year to work as a pig farmer at a May Seventh Cadre School in rural Henan.

He published an influential article connecting the previously-undeciphered numeral symbols on Zhou-era ritual bronzes to the hexagram forms used in the Mawangdui Silk Text copy of the I Ching divination following its discovery in the 1970s.

[2] While taking the exams of his preferred school, Tsinghua, he felt that a paper he had submitted during the Chinese literature examinations had incorrectly responded to the prompt, and left the testing early.

Although seeking to attend the university's Chinese department, he settled instead for History due to low scores on an English examination.

During his final year at the university, he wrote a lengthy letter to Hu Shih, arguing that the 16th-century novel Investiture of the Gods was initially written by a Daoist priest named Lu Xixing (陸西星).

Impressed by Zhang's research, Hu wrote back favorably, and the letter was published in the Duli Pinglun (獨立評論) journal.

Although the institution later moved operations to Longquan in Kunming, Yunnan, to avoid Japanese air raids, the library remained in Hunan for some time.

During his time at Peking, Zhang wrote a number of journal articles on vernacular literature and the Dunhuang manuscripts, as well as an influential analysis of Song Jiang.

He disagreed with the idea that feudalism originated during the Warring States period (475–221 BCE), instead believing it emerged during the Cao Wei and Jin dynasties (220–420 CE).

[8] In 1966, Zhang was promoted to a senior research fellowship by Yin Da (尹達), a close colleague who served as acting director of the CASS's Institute of History.

The same year, the outbreak of the Cultural Revolution led to Zhang's assignment to a May Seventh Cadre School in rural Henan, where he worked as a pig farmer as part of a mass political re-education campaign.

Various historians were recalled from these rural programs in 1971, after Premier Zhou Enlai ordered the Zhonghua Book Company to continue a stalled project to publish modern versions of the official dynastic histories.