This paper discussed the effects of nano-silica hydrophobic coating on properties of kraft and corrugatedcardboard. The nano-silica and silicone resin were blended to prepare hydrophobic coating, which was dipped and sprayedon the surface of kraft and corrugated board. Effects of hydrophobicity were evaluated by contact angle and Cobb waterabsorption. Mechanical properties of kraft and corrugated board were evaluated by tensile strength, folding strength, tearingresistance, bursting strength, compression strength, flat crush strength, puncture strength. The contact angle of hydrophobicpaper after treatment with blended resin was 88.6° and Cobb water absorption obviously decreased. With increasing layernumber of the coating, the burst strength of kraft paper and the flat crush resistance of corrugated cardboard both showed arising trend. After treatment with double coating, all the physical properties of the corrugated board were greatly improved,and the mechanical properties of nano-silica double-coated corrugated cardboard were better than those of the corrugatedboard with single layer of coating. Paper and paperboard treated by hydrophobic treatment did not only show improvementin the hydrophobic properties of paper and cardboard, but also enhancement in the physical properties of paper andcardboard, which provides a theoretical basis and treatment method for the realization of waterproof packaging of paper orpaperboard.