Abstract Multiferroic magnetoelectric (ME) composites are widely discussed for new kinds of smart structures. However, studies on nonlinear ME coupling in layered composites with nano-scale thickness which have unique superiorities are rather limited. It is well known that the physical and mechanical properties of nanostructures are size-dependent. Considering surface effect and nonlinear material characteristics, this work proposes a nonlinear theoretical model for ME nanocomposites with different magnetostrictive materials based on the surface stress model. The results show that surface effect can enhance the ME coupling in the composites with nano-scale thickness. The ME voltage coefficient can be suppressed due to the consideration of flexural strain and imperfect interfacial conditions. The weak-bonding interface makes the optimal volume fraction shift to PZT-rich composites. Moreover, when subjected to combined pre-stress and magnetic loadings, ME nanocomposites exhibit complex magneto-mechanical coupling characteristics. The proposed model provides a method to analyze and evaluate the nonlinear ME coupling characteristics of nanostructures-based devices.