Waste ternary lithium-ion batteries are very harmful to the environment and humans, but the valuable metals such as lithium, nickel, cobalt, and manganese have high recycling value. In this paper, the mechanically crushed ternary lithium battery is used as the raw material, The microwave dielectric properties and absorption properties of the cathode powder with temperature change are studied. Analysis is mainly based on the dielectric properties and microwave absorption properties of the cathode powder. The results show that the cathode powder has good microwave absorption performance between 25-700°C, The dielectric constant ?r' reaches the maximum value of 11.96 (F/M) at 400°C. as the microwave power increases, the time for the cathode powder to rise to 700°C is significantly shortened, and the maximum heating rate is in the range of 320-450°C. The change trend of dielectric properties is consistent with the change trend of microwave heating characteristics.