A wood-based composite exhibiting excellent electromagnetic shielding performance was prepared by electroless Ni plating. The properties of the material were characterized by a series of tests. The results showed that the growth route of Ni particles was first arranged along the inherent grain of the wood to form a banded metal layer. With extension of the duration of electroless plating, the growth of Ni particles gradually extended around and filled the pores between wood fibers, and finally formed flake-shape structure. The metal coatings formed a strip along the inherent grain of the wood surface and then changed into a sheet until it covered the entire wood surface. The coatings resistance was from 12 Ω to 0.5 Ω with the increase in duration of electroless plating. When the duration was 20 min, the composite coating resistance was 0.5 Ω. Here, the contact angle of composite coatings was 98.3° when the plating time was 15 min. When the wood surface was modified via two depositions of Ni, the average electromagnetic shielding value of the composites was over 80 dB in the frequency ranging from 0.3 kHz to 3.0 GHz.