As a high school student, Sickman became interested in Japanese and Chinese art. In 1930, he earned a degree in the field at Harvard, where he also became fluent in Chinese. He traveled throughout China under the newly formed Harvard-Yenching Fellowship, purchasing Chinese paintings, sculpture and furniture for collection and study at the William Rockhill Nelson Gallery of the Nelson-Atkins Museum. He traveled on a scholarship to China, where he met Langdon Warner, his former Harvard professor and one of the trustees of the Nelson museum, which was being established. Warner, who had been appointed to build a collection for the museum, initially tutored Sickman. Sickman was later given the responsibility of buying works on his own by means of a $11 million donation by Kansas City Star founder William Rockhill Nelson.
In 1931, Sickman joined the staff of the Nelson-Atkins Museum of Art. In 1935, he became the curator of Oriental Art at the museum. His museum curatorial career was interrupted by military service in the Second World War.
World War II
Sickman's war service took him to Tokyo during the occupation of Japan where he served as one of the "Monuments Men" under  General Douglas MacArthur's Monuments, Fine Arts, and Archives (MFAA) section. Among those serving with Sickman in Tokyo were Sherman Lee and Patrick Lennox Tierney.
Curatorship after World War II
At war's end, he returned to the Nelson-Atkins museum, where he was director from 1953 through 1977.
- 1956 – The Art and Architecture of China (with Alexander Coburn Soper). Baltimore, Maryland: Penguin Books. OCLC 192176467
- Roberts Commission
- Monuments, Fine Arts, and Archives program
- Monuments Men Foundation for the Preservation of Art
- McGill, Douglas (11 May 1988). "Laurence Sickman, Scholar and Expert In the Art of China]". New York Times. Retrieved 30 December 2009.
- Monuments Men Foundation: Monuments Men> Sickman, Maj. Laurence.
- Freer Gallery of Art (1973).
- Weber, Bruce. "Sherman Lee, Who Led Cleveland Museum, Dies at 90," New York Times. July 11, 2008; Kappes, John. "Sherman Lee, who led the Cleveland Museum of Art to global renown, dead at 90," The Plain Dealer (Cleveland). July 9, 2008.
- Consulate General of Japan, Los Angeles: Order of the Rising Sun, Gold Rays with Neck Ribbon (3rd class). Archived 2011-10-04 at the Wayback Machine.
- WorldCat: Sickman, L. C. S. (Laurence C. S.)
- American Commission for the Protection and Salvage of Artistic and Historic Monuments in War Areas. (1946). Report. Washington, D.C.: U.S. Government Printing Office. OCLC 185537904
- Freer Gallery of Art (1973), Fifth presentation of the Charles Lang Freer medal, September 11, 1973 (PDF), Washington, D.C.
- Nicholas, Lynn H. (May 1995) . The Rape of Europa: The Fate of Europe's Treasures in the Third Reich and the Second World War. New York City: Vintage Books. ISBN 978-0-679-40069-1. OCLC 32531154.