Archimedes (287 BC ~ 2 BC12) was an ancient Greek mathematician, physicist, astronomer and engineer. His contribution to the lever principle, density, buoyancy and hydrostatic pressure was considered as one of the milestones of science and mathematics at that time. In his masterpiece On Lever, he systematically expounded the principle of lever and related concepts, which played an important role in solving a series of physical problems, especially in architecture and machinery.

Mozi (about 470 ~ 390 BC) was a famous philosopher, scientist and engineer in ancient China. His contribution mainly lies in the invention of many mechanical devices, such as crossbows, ghost spirits, Mozi cannons and so on. These inventions greatly promoted the development of ancient military and engineering in China. However, it is not clear whether Mozi discovered the lever principle, and there is no relevant record in the Mohist Scriptures and Luoshu in ancient China.

Therefore, the person who discovered the lever principle was the ancient Greek mathematician Archimedes.