In Wire Arc Additive Manufacturing (WAAM), residual stress is easily generated during solidification and subsequent cooling, which affects the formation and use of the components. In this paper, finite element simulations are carried out to investitgate the influence of roller reductions on the temperature, stress, strain and residual stress distribution in components during the hybrid forming of Ti-6Al-4V alloy by WAAM and interlayer rolling. The results show that interlayer rolling reduce the residual macroscopic stress significantly in the deposited metal, and at the same time reduce the overall stress on the substrate. Increasing reduction can reduce significantly the macroscopic residual stresses and distorsion of the components. The microstructure of the material can be changed dramatically by the plastic deformation after rolling, which lead to a new route for the optimization of the microstructure during additive manufcturing.