In 678, Tang forces commanded by the chancellor Li Jingxuan, suffered a major defeat at the hands of Tufan's general Gar Trinring Tsendro ("Lun Qinling" (論欽陵) in Chinese), and the major general Liu Shenli (劉審禮) was captured.
It was said that because Guo had been at the legislative bureau for a long period and was familiar with how it was run, most of the edicts were drafted by him, and he was considered capable in this.
In 683, when Emperor Gaozong became seriously ill, he had Guo, along with Pei Yan and Liu, assist his crown prince Li Zhe in handling important matters of state.
Soon after Emperor Zhongzong's ascension, around the new year 684, she made Guo Zhengyi the principal of the imperial university, no longer a chancellor.
For the next few years, Guo was moved between several positions—first as the prefect of Jin Prefecture (晉州, roughly modern Linfen, Shanxi), then the deputy head of the archival bureau (by this time known as Lintai Jian (麟臺監)), then acting prefect of Shan Prefecture (陝州, roughly modern Sanmenxia, Henan).