To address the potential adverse impact of silane on cement hydration, this study systematically investigates the effects of power ultrasound on the mechanical and hydrophobic properties, and the microstructure of silane-modified cement paste. Experimental results showed that ultrasonic treatment within the 240–720 W range significantly enhanced the compressive strength compared to the reference group. In particular, the 480 W group exhibited increases in compressive strength of 36.9 %, 10.7 %, and 7.9 % at 1, 3, and 28 days, respectively. X-ray diffraction and TG analysis revealed that this treatment accelerated the dissolution and hydration degree of the clinker. Contact angle measurements indicated that optimal hydrophobic performance was achieved at 720 W, with a contact angle of 133.0°, representing a 34.2 % increase compared to the reference group. These findings indicate that power ultrasound holds excellent potential for preparing the hydrophobic cementitious materials.