He is considered to be one of the foremost figures in modern Chinese archaeology and his work was instrumental in proving the historical authenticity of the Shang dynasty.

In 1925 and 1926 he conducted archeological excavations of the Yangshao culture in the southern part of the Shanxi province, for which he was invited to join the Freer Gallery of Art in Washington D.C. as a field worker.

The recovered artefacts comprised among others early bronze casts and a large number of oracle bones, which represent the earliest significant body of ancient Chinese writing.

[1][4] During his career Li mentored a generation of Chinese archaeologists including Xia Nai, Kwang-chih Chang, and Guo Baojun.

During the third excavation of Yinxu in 1929, Li Ji discussed the pioneers of the "Xiaotun Culture" based on a piece of painted pottery unearthed in the strata.

On the other hand, he also criticized the limitations of Chinese scholars and paid too much attention to cultural exchanges in East Asia and surrounding areas.