W/Ta nanoscale metallic multilayer is a typical body-centered cubic/ body-centered cubic nanolayered composite，which is very promising for the application in nuclear fusion devices. Based on atomistic molecular dynamic（MD）simulations，we investigate the mechanical properties and plastic deformation mechanisms of W/Ta nanolayered composite under uniaxial tension，and further analyze the influence of modulation period on the mechanical response of W/Ta nanolayered composite. The results show that the W（110）/Ta（110）interface forms a misfit dislocation network，which can not only serve as the source for dislocation nucleation but also adsorb the dislocations in the metallic multilayer. The microstructure evolution analysis shows that，W/Ta nanolayered composite mainly experiences three deformation stages during stretching，i.e. linear elastic，plastic yield，and plastic flow stages. The dislocations firstly nucleate and propagate in the Ta layers，which leads to the sharp drop in the stress-strain curve. Subsequently，the dislocations in the Ta layers pass through the interfaces and enter into the W layers，and the propagation and slip of the dislocations in the W layers cause the yield of W layers. The yield of the sample is primarily determined by the Ta layers，and the plastic deformation in the flow stage is jointly governed by the dislocations and their evolution in both the W and Ta layers. With an increase of modulation period，the number of interfaces in the W/Ta metallic multilayer decreases，so that the nucleation of dislocations decreases as well as the amount of dislocations adsorbed by the interfaces decreases. In addition，the decreased number of the interface weakens the effect of hindering dislocations by interface. Therefore，the yield strength increases and the averaged plastic flow strength decreases.