A novel sonocatalyst, Er3+:Y3Al3O12/KNbO3 composite, was synthesized, and then, characterized by Xray diffractometer (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). In order to evaluate the sonocatalytic activity of prepared Er3+:Y3Al3O12/KNbO3 composite, the sonocatalytic degradation of ketamine, a kind of narcotic drug, was studied. In addition, some influencing factors such as mass ratio, heat-treated temperature and heat-treated time on the sonocatalytic activity of prepared Er3+:Y3Al3O12/KNbO3 powders and ultrasonic irradiation time on the sonocatalytic degradation of ketamine were examined by using GC -MS machine. The experimental results showed that the Er3+:Y3Al3O12/KMO3 composite is a good sonocatalyst in the field of ultrasonic chemistry and the sonocatalytic degradation was an effective method for the innocent treatment of ketamine. (C) 2016 Elsevier B.V. All rights reserved.