The additive manufacturing process (i.e. Selective Laser Melting) allow us to produce lattice structures which have less weight, higher impact absorption capacity and better thermal exchange property compared to the classical structures. Unfortunately, geometrical imperfections in the lattice structures are by-product results of the manufacturing process. These imperfections decrease the lifetime and the strength of the lattice structures and alterate their mechanical responses. The objective of the paper is to present a simulation strategy which allows us to take into account the effect of the geometrical imperfections on the mechanical response of the lattice structure. In the first part, an identification method of geometrical parameters of the lattice structure based on tomography measurements is presented. In the second part, a finite element model for the lattice structure with the simplified geometrical imperfections is obtained. In what follows, based on experimental tests, distributions of geometrical imperfections are proposed. Based on these distributions, a mathematical approach is presented to propagate the effect of uncertainties of the geometrical imperfections on the strength variability of the lattice structure.