Materials with negative poisson's ratio(auxetic)are subsetofmetamaterialthatoften highly regarded in laboratoryand academic research. Previous research indicates, however, thattheAuxetic behaviorcan lead to improve material properties, such as resistance to indentation and impact strength. The aim of this study is to investigate the effect of auxetic coreofa sandwich panel on the panel resistance to projectile impact. During this study, after reviewing previous litratures, by selecting the geometryofauxetic from previous researches, through finite element method (FEM) analysis, a auxetic cellular structure with the greatest strength for core desigofandwich panel is choosed. Then selected auxetic cellular structure, built on a laboratory scale by Additive manufacturing method and been test by quasi-static pressure. The results were compared with the results of FEM analysis and that was followed proper convergence. Then the operation of the auxetic cellular structure as the coreofa sandwich panel, under the impact of a rigid projectile, with a kelvin structure and two-dimensional hexagonal structurewere compared. Based on results of this comparison that was done by FEM analysis, deal with the auxetic core panel, compared to non-auxetic core panel, projectiletops faster and has less penetrate in target; While the Auxetic panel has least lastic deformation and back facet displacement than other panels. As a result, panel made of auxetic cellular structure that used in this study showed a better impact strength against a projectile. Keywords: Auxetic, Metamaterial, Impact strength, Composite structure, Cellular structure, Additive manufacturing, Selective laser sintering