The chemisorption of acetylene molecules on a reconstructed diamond (001)-(2×1) surface and the dynamic behavior of this reaction are studied by molecular dynamics simulation using many-body interatomic Brenner (#2) potential. Six chemisorption configurations are observed. About 95% of the chemisorption events invole the formation of two C—Cs bonds between the acetylene molecule and the diamond surface. The dependence of the adsorption configuration upon the binding energy, the incident energy and the position of the molecule, as well as the local spatial structure of the diamond surface are analyzed. In order to provide an intensive understanding of the chemisorption, snapshots of atomic position are provided. The energy exchange characteristics between the incident molecules and the surface are discussed.