采用分子动力学方法(MD)对单层石墨烯纳米片(GNPs)与单面及双面Ni包覆单层GNP (Ni-GNP、Ni-GNP-Ni)增强镁基复合材料(GNP/Mg、Ni-GNP/Mg、Ni-GNP-Ni/Mg)在单轴拉伸作用下的力学性能进行了研究，并与含有空位缺陷的双面Ni包覆单层GNP (Ni-defected GNP-Ni)及双面Ni包覆多层GNPs (Ni-nGNPs-Ni)增强镁基复合材料(Ni-defected GNP-Ni/Mg、Ni-nGNPs-Ni/Mg (n为GPNs层数))拉伸性能进行了对比。研究结果表明：GNPs的加入可以显著增强镁基复合材料的力学性能，与单晶Mg相比，GNP/Mg纳米复合材料在300 K及应变速率为1×10⁹ s^-1时的拉伸强度和弹性模量分别提高了32.60%和37.91%，而Ni-GNP-Ni/Mg的拉伸强度和弹性模量分别提高了46.79% 和54.53%；此外，Ni-defected GNP-Ni/Mg复合材料的弹性模量和拉伸强度较GNP/Mg有较大的提高，但其断裂应变提高的幅度较小；而Ni-GNP/Mg复合材料的拉伸强度和断裂应变较GNP/Mg有较大的提高，但其弹性模量提高的幅度较小。Ni-GNP-Ni/Mg基复合材料的弹性模量、拉伸强度和断裂应变随着温度的升高而降低，表现出了温度软化效应，但复合材料弹性模量的变化对温度不敏感。随着Ni-nGNPs-Ni中n的增加，即增强体体积分数增大时，复合材料弹性模量、拉伸强度及断裂应变均随之增大，复合材料表现出良好的综合力学性能。最后通过对原子结构演化的分析，发现Ni-GNP-Ni/Mg纳米复合材料的强化机制主要是界面强化、载荷的有效传递及位错强化。

To improve the mechanical properties of Mg alloys and broaden their application fields, high performance Mg matrix nanocomposites have received more and more attention nowadays. Therefore, the research on the basic mechanical properties and strengthening mechanism of new Mg matrix composites at nanoscale has important theoretical and practical significance. The mechanical properties of pristine single-layer graphene nanoplatelets (GNPs) and single-side and double-side nickel-coated GNP (Ni-GNP, Ni-GNP-Ni) reinforced Mg composites (GNP/Mg, Ni-GNP/Mg, Ni-GNP-Ni/Mg) are studied under uniaxial tension by molecular dynamics (MD) simulations. Meanwhile, their tensile properties are also compared with those of double-side nickel-coated GNP with vacancy defects (Ni-defected GNP-Ni) and double-side nickel-coated multilayer GNPs (Ni-nGNPs-Ni) reinforced Mg-based composites. The simulated results show that the mechanical properties of Mg matrix composites are improved significantly by the addition of GNPs. Compared with single crystal Mg, the tensile strength and elastic modulus of GNP/Mg nanocomposites at 300 K and 1×10⁹ s^-1 are increased by 32.60% and 37.91%, respectively; while the tensile strength and elastic modulus of Ni-GNP-Ni/Mg composites are increased by 46.79% and 54.53%, separately. In addition, there is a larger increase in the elastic modulus and tensile strength but a smaller increase in the fracture strain for Ni-defected GNP-Ni/Mg composites, while there is a larger increase in the tensile strength and fracture strain but a smaller increase in the elastic modulus for Ni-GNP/Mg composites as compared with those of GNP/Mg composites. The elastic modulus, tensile strength and fracture strain of Ni-GNP-Ni/Mg composites decreases with increase in temperature, showing a temperature softening effect, but the variation in the elastic modulus of the composites is insensitive to temperature. With increasing of the layers or volume fractions of GNPs in Ni-nGNPs-Ni, the elastic modulus, tensile strength and fracture strain of the composites are all increased significantly, and the composites show excellent comprehensive mechanical properties. It is concluded that the main strengthening mechanisms for Ni-GNP-Ni/Mg nanocomposites are strong interface bonding, effective load transfer from the Mg matrix to the Ni-GNP-Ni and dislocation strengthening by analysis of the evolution of atomic structure.