The influence of high-intensity ultrasound on the microstructure and the distribution of solute elements Si in α (Al) of Φ10mm Al-1% Si alloy bonding wire produced by horizontal continuous casting have been investigated. Experimental results show that under high-intensity ultrasonication the microstructure is refined, the solid solubility and the uniformity of the distribution of Si in α (Al) are improved and the solute segregation is suppressed. The effect of high-intensity ultrasonic vibration on restraining solute segregation in Al-1% Si alloy ingot in horizontal continuous casting is explained from such factors as the diffusion of solute, solidification interval, solidifying front shape, temperature field, flow pattern and microstructure.