He was a colleague and collaborator of Matteo Ricci, the Italian Jesuit. Together they translated several classic Western texts (most notably part of Euclid's Elements) into Chinese, as well as several Chinese Confucian texts into Latin.[12] Ricci's influence led to Xu being baptized as a Roman Catholic in 1603, under the name "PaulSiu". His descendants remained as Catholics and Christians into the 21st century[citation needed].

From 1607 until 1610, Xu was forced to retire from public office, and returned to his home in Shanghai. It was during this time that he experimented with Western-style irrigation methods.[11] He also experimented with the cultivation of sweet potatoes, cotton, and the nu zhen tree.[11] He was called once more to serve the Chinese bureaucracy, where he rose to a high rank and became known late in his career simply as "The Minister".[12] Yet he continued to experiment and learn of new agricultural practices while he served his office, promoting the use of wet-rice in the Northeast of China.[11] From 1613 until 1620 he often visited Tianjin, where he helped organize self-sufficient military settlements (tun tian).[11]

Xu Guangqi's tomb still exists in Shanghai in Guangqi Park just a short walk from the Xujiahui Cathedral in theXujiahui area on Nandan Road (南丹路).