A method for the induction of the agglomeration of different kinds of particles by the ultrasonic irradiation in the water was studied. This method has been proven to be applicable to the separation of photo-catalyst particles from the drainage of photo-oxidation process. The catalyst particle was titanium oxide with the average diameter of 3 mu m. The agglomeration was observed when the ultrasound with the frequency of 26 kHz and the power of 80 W was irradiated and a certain amount of glass beads with the diameter between 33-34 mu m were added. The catalyst particles deposited on the glass beads, and then settled together with the glass beads leading to the liquid-solid separation. It was also found that the addition of the glass beads has also enhanced the agglomeration among the catalyst particles themselves.