This study examines the effect of the loss-damping η coefficient and the stress magnetostrictive coefficient δ on the magnetoelectric (ME) phenomenon in bi-layer composites consisting of a polyurethane layer loaded with magnetic Fe3O4 nanoparticles glued to piezoelectric ceramic. A model based on a driven damped oscillation system has been developed to evaluate the influence of the η and δ coefficients on ME current response (iME) versus bias magnetic induction (Bdc). A good agreement was obtained between the simulated and experimental results; additionally, the magnitude of ME current increased with an increase in Bdc, and also increased with an increase in δ and a decrease in η. However, the phase shift ϕ between iME and alternative magnetic induction Bac presents a phase-switching phenomenon—namely, the point at which the curve ϕ(Bdc) switches by π displaced from the center (Bdc=0T)—as well as the curve displaced toward lower when η increased or δ decreased. Consequently, the ME current and the phase-switching phenomenon are mainly influenced by the magnetostrictive and the loss-damping coefficients.