Abstract: Introducing crystalline dendrites can effectively enhance the plasticity of metallic glass matrix composites. In this study, the mechanical behaviors of numerical samples containing dispersed dendrites under uniaxial tensile loading were studied through large-scale molecular dynamics simulations. The results indicate that the degree of aggregation of the dendrites significantly affects the behavior of shear bands in the materials and ultimately leads to different tensile plasticity. When the dendrite volume fraction is relatively low, the plastic deformation of composites is dominated by the mechanism of shear band formation via the initiation of STZ atoms. Conversely, when the dendrite volume fraction is high, the plastic deformation of the material is primarily governed by dislocation slip within the dendrites. In the case of medium dendrite volume fractions, both mechanisms co-exist and interact with each other, resulting in a complex and non-monotonic trend of the yield stress and plastic deformation capability as the degree of dendrite aggregation changes. This work is aimed at providing guidelines for the design of metallic glass matrix composites with complex second phase dendritic structures.