The "Grey's Anatomy" star started a nonprofit foundation last year to improve the lives of people in the West African nation.
"The stories of innumerable Sierra Leoneans that were forced into slavery have yet to be extensively told," Washington said in a statement. "I believe this project will begin to shed some much-needed light on the region, both past and present."
The computer project focuses on Bunce Island, an 18th-century slave-trading castle that sent African captives to North America. Joseph Opala and Gary Chatelain, professors at James Madison University in Virginia, are directing the project, which will show the castle as it appeared in 1805.
They hope to create an educational CD that will let students look at the castle and its details to see what Africans experienced 250 years ago.
"Our computer animation project will allow us to go beyond the imagination, and actually see how the Atlantic slave trade was carried out," which is crucial because events then could not be documented by photography, Opala said in a statement.
Washington's donation was made through his Gondobay Manga Foundation and the Friends of Sierra Leone, a spokesman said Wednesday.
The star of ABC's hit medical drama came under fire this year for using an anti-gay slur, for which he later apologized.