From 1989-1990, he helped conduct a nationwide survey on sexual behavior and attitudes in China, not unlike the Kinsey Report in the United States. A report on the survey's outcomes was first published in 1992 in Shanghai; in 1997 Liu published the English edition Sexual Behavior in Modern China (ISBN 0-8264-0886-9). Also in 1997, he opened China's first sex museum in Shanghai; it has since moved to Tongli.
Liu won the Magnus Hirschfeld Medal for his research in sexology in 1994.
Liu published several books on the history of erotica in China:
- History of Erotica in China (2004), People's Daily Press, ISBN 7-80153-776-9 (in Chinese)
- Pictorial History of Erotica.
- World Sex Culture (2005), China Friendship Press, ISBN 7-5057-2110-0. (in Chinese)