Yunnan snub-nosed monkeys, Yunnan province, 1995 [Photo/Wild China Film]

In 1995 he filmed the documentary Mystery of the Yunnan Snub-Nosed Monkey. It was the first time humans had recorded the activities of the monkeys on film. Xi started work on another documentary, Mystery Monkeys of Shangri-La, in 2012.

In 1997 he entered Hoh Xil Nature Reserve in Qinghai and took direct photographic evidence Tibetan antelopes had been poached.