Abstract: This study investigates the application of ultrasonic waves to enhance the sedimentation and thickening efficiency of unclassified tailings slurry. Single-factor tests were first conducted to identify the optimal ultrasonic conditions and preliminary flocculation parameters and obtain sedimentation velocity and underflow concentration of the slurry. Response surface Methodology (RSM) was employed to determine the optimal flocculation parameters and sedimentation velocity and to investigate the ultrasonic-induced sedimentation mechanism of tailings slurry. Results show that: ① When ultrasonic waves at 20 kHz and 90 W were applied for 10 minutes after 3 minutes of sedimentation, the slurry sedimentation velocity reached 128.16cm/h, and the underflow concentration was 70.3% after 2 hours of sedimentation, a 4.24 percentage points improvement over natural sedimentation. ② Under ultrasonic conditions, the addition of 30 g/t of CPAM with a concentration of 0.1% and a molecular weight of 12 million reduced the rapid sedimentation time from 15 minutes to 3 minutes, achieving a sedimentation velocity of 537.84 cm/h and an underflow concentration of 70.27%. ③ RSM optimization revealed that adding 30.72 g/t of CPAM with a concentration of 0.11% and a molecular weight of 11.76 million resulted in an optimal sedimentation velocity of 573.96 cm/h. ④ Ultrasonic waves achieved slurry floc densification through cavitation and thermal effects, thereby enhancing slurry thickening efficiency.