He gained international recognition in the late 1980s with Book from the Sky, a monumental installation composed of books and scrolls printed with what appear to be traditional Chinese characters. The texts are illegible, however, because all the characters were invented by the artist, exposing the unreliability of the written word as a primary vehicle of communication. He later came up with the Square Word Calligraphy system, which renders English words through Chinese brushstrokes. Chinese readers are frustrated because it seems like they should be able to read the letters and words, but can't. English readers see the Chinese-looking script and immediately dismiss it as illegible. It is only after the trick is pointed out that they realize they can actually read the writing.
Xu moved to the United States in 1990, where his work has continued to focus on written language. In 1999 he was awarded a MacArthur Fellowship for his originality, creativity, and capacity to contribute to society, particularly in printmaking and calligraphy. In 2008, Xu returned to China to serve as the vice president for international relations at the Central Academy of Fine Arts. His work has been exhibited in many countries including China, Japan, Australia, the United States, and Europe.