In this study, a colloidal suspension, composed of polymethylsilsesquioxane (PMS) and Cu-containing nanoparticles (CuNP), was prepared through simple neutralization reaction using sodium methyl siliconate (SMS) and CuCl₂solutions. The nano-structure of CuNP was investigated by TEM and the results showed that lamellar crystal Cu(OH)₂with size of around 10 nm was imbedded in PMS nano-particle. The FTIR also confirmed the presence of small amount of PMS in CuNP. The specific nano-structure of CuNP resulted in excellent thermal stability based on TG analysis. After dip-coating in optimized conditions and drying, a PMS/CuNP xerogel coating layer was generated at the bamboo surface, endowing superhydrophobic and excellent anti-mildew performance according to ASTM D3273-16. The water contact angle (WCA) reached up to 151.3 ± 1.9° and the mildew resistance grade was marked as 10 where no mold was found at the surface after 4 weeks incubation.