Abstract: The experiment used ultrasound to remove COD and NH3-N in landfill leachate. By orthogonal design，the effect activated Carbon, pH,ultrasonic power，irradiation time and aeration time exert on the removal rate of COD and NH3-N is worked out. The results show that：effect of the pretreatment experiment is best when activated Carbon is 1.0g，pH is 9，ultrasonic power is 360w，irradiation time is 6min and aeration time is 6min，of which the removal rate of COD is 63.7% and of NH3-N is 80.24%.