Abstarct: With the development of nanotechnology, the applications of mextallic materials have considerably increased in this new field of technology. Analyzing the mechanical properties and behaviors of mextals as one of the constituents of nanodevices and determining the effects of parameters related to loading conditions are essential steps. On the other hand, the researchers have always tried to improve the properties of mextal matrix composites by utilizing suitable reinforcements. Nanostructures like carbon nanotubes have been employed to reinforce and enhance the mechanical characteristics of nanocomposites as new engineering materials. It has always been attempted to analyze the properties of nanocomposites by experimental and computational methods and to obtain the effects of nanostructures addition on their mechanical behaviors. With regard to that the experimental methods are expensive and time-consuming in nanomaterials fields, molecular dynamics simulation method as a reliable and accurate computational method can be an appropriate alternative method. In present research, the purposes are to study mechanical properties and deformation mechanism of mextals at nanoscale point of view and to investigate mechanical characteristics of nanocomposites reinforced with nanostructures baxsed on molecular dynamics simulations. To do this, carbon nanotubes (CNTs), boron nitride nanotubes (BNNTs) and graphene are employed to combine with mextallic matrices in order to improve their mechanical properties. The research which are intended to be performed in this purpose are classified into two distinct categories, namely crystalline mextals and mextallic glasses (MGs). In the first category, mextal matrices have crystalline structures and are reinforced with BNNT and graphene. While, in the second category, the atomic structure of mextal matrices is amorphous and they are combined with CNT and graphene with reinforcing purposes. First, mechanical properties and deformation mechanism of nano single crystal aluminum are investigated and the applied strain rate and system temperature effects are attained. According to the obtained results, strain rate does no cause considerable effects on the mechanical behavior on the material. But the system temperature makes significant influence. After that BNNT are utilized to reinforce aluminum material and stress-strain curve and influences of the nanotube on the nanocomposite are achieved by modeling tensile and compressive loading tests. Results show high reinforcing effects of the long BNNTs of the matrix. Then a new emerging group of engineering materials, namely nanolaxyered composites are explored in which alternating laxyers of mextal and graphene are mixed to reinforce various fcc mextals, i.e. copper, aluminum, nickel, silver and gold. Graphene addition and also mextal laxyer thickness make significant influence on the compressive deformation mechanism of the composites baxsed on Cu, Au, and Ag matrices. In the continuation of the research, CNTs are used in order to improve mechanical characteristics of Cu-Zr MGs. Elastic-plastic behavior of the nanocomposite are derived by tensile and compressive loadings. Also the effects of the reinforcement parameters are studied. Long CNT addition significantly improve the mechanical characteristics of MG matrix. Being brittle is one of the intrinsic properties of MGs. Also they have a very low ability in absorbing an applied loading energy. Hence, combining of graphene laxyers with MG matrices are recommended as a solution to improve their ductility. To do so, long and short graphene nanosheets of different arrangements are utilized to improve the ductility and toughness of MGs. According to the obtained results graphene laxyers can significantly enhance the ductility and toughness of glassy mextals by blocking the propagation of the formed shear bands and by increasing the number of local plastic deformations.