In order to investigate the synergistic effect of different deformation modes (dislocations and local atomistic rear-rangements) on the strength of mixed crystalline and amorphous materials, tensile and compressive deformation analyses of a two-dimensional binary system with various microstructures were carried out using molecular dynamics simulations. The binary system is composed of atoms with two different atomic radii. By varying the mixing ratio and the interac-tion force between different atoms, 66 binary system models with various structures are represented, and each model is classified into three categories: crystalline, amorphous, and mixed crystalline/amorphous models by structural analysis. Deformation analysis shows that the strength of the mixed crystalline/amorphous models tends to be weaker than that of the crystal and amorphous models. The reason for this is that the edge of the force chain in the amorphous phase appears at the crystalline/amorphous interface, where dislocation release from the interface to the crystalline phase occurs easily.