Abstract: The influences of the misfit nature on the structure of two-dimensional aluminum film and its nucleation mechanism are studied by using the methods of three-dimensional molecular dynamics simulation and many-body potential function of embedded atom method (EAM) created by Ercolessi and Adams, and simulating the processes of misfit dislocations in two-dimensional mismatch aluminum film crystal. The result shows that under the same conditions, the critical thickness of negative mismatch is smaller than that of positive mismatch; the negative mismatch is prone to misfit dislocation; the negative misfit dislocation is formed from gap atomic group in a downward-pointing triangle on its surface; the positive misfit dislocation is made from distorted region on atomic surface; when the structure is stable, the negative mismatching system will extrude local atomic layer on its surface; the positive mismatching system will start to collapse.