Abstract: In recent years, lithium-ion batteries using nickel-cobalt-manganese ternary materials as cathode materials have advantages of good electrical performance, high specific energy, green environmental protection, low cost, and high discharge stability. These have been widely used in new energy vehicles and portable electronics product areas. As a new generation of rechargeable batteries, lithium batteries have a certain service life, which is generally 3–5 years. Therefore, the rapid development of lithium-ion batteries has caused a blowout increase in the number of used lithium-ion batteries. Waste ternary lithium-ion batteries are very harmful to the environment and humans, but valuable metals such as lithium, nickel, cobalt, and manganese have a high recycling value. In terms of resource recycling and environmental protection, used lithium-ion batteries have a high recycling value. At present, the recycling of waste lithium-ion batteries is facing some problems. For example, the diversity of electrode materials makes their separation and purification difficult, and the high cost can also cause some problems such as secondary pollution. Therefore, it is necessary to find green and low-cost methods for the recycling of waste lithium-ion batteries. Microwave metallurgy has outstanding advantages in this respect. Therefore, this paper used the mechanically crushed ternary lithium battery as the raw material for studying the dielectric properties of the apparent density of the positive electrode material at room temperature and the microwave dielectric properties and absorption that change with temperature. Results show that at room temperature, the cathode material has the best dielectric performance at an apparent density of 1.484 g·cm^–3. During the heating process, the cathode material has good microwave absorption performance at 25–700 ℃. At 400 ℃, the dielectric constant \textitε_\rmr^' reaches the maximum value of 11.96 F·M^–1. With the increase in the microwave power, the time for the positive electrode powder to rise to 700 °C is significantly shortened, and the maximum heating rate is in the range of 320–450 °C. The changing trend of the dielectric properties is consistent with the changing trend of the microwave heating characteristics.