The urgent requirement of carbon reduction in the world provides wood products a historical opportunity to play a crucial role to fix carbon dioxide and reduce carbon emission. It is essential to reveal the in situ growth mechanism of copper nanoparticles on eucalyptus scrimber surface. Cu4(SO4)(OH)6 nanoflowers are in situ synthesized successfully on the surface of eucalyptus scrimber via a simple hydrothermal process in this work. The detailed nucleation and in situ growth process of Cu4(OH)6SO4 nanoparticles on the surface of eucalyptus scrimber, characterized by the trajectory of size evolution, are revealed first in this work. According to the classical nucleation theory, the nucleation stage of as prepared Cu4(SO4)(OH)6 nanoflowers includes nucleus formation and nucleus growth. Although the same initial precursor reactant is obtained at the nucleation stage, there are two types of early nanoparticles, with morphology of fusiform and strip shape being self assembled to nanoflower structure during the growth stage. Further, the modified eucalyptus scrimber exhibits excellent superhydrophobicity, UV durability, mold and moisture resistance, as well as reversible property. Therefore, the proposed in situ growth kinetics related to Cu4(OH)6SO4 nanoparticles on wood surface have potential to be a reference to develop multifunctional superhydrophobic wood-based material for variable applications.