Spent lithium-ion batteries(LIBs) contain lots of valuable metals such as nickel, cobalt, and lithium, together with organic solvents, binders, and other toxic materials. Therefore, recycling of spent LIBs is of great importance for comprehensive resource recovery and environmental protection. In this study, vacuum pyrolysis was used to dispose of the cathode sheets of LIBs. The effects of pyrolysis temperature and vacuum degree on the separation of cathode sheets and phase transition of valuable metal of cathode active powder were investigated in detail. The results showed that the effective separation of active powder and Al foil can be achieved under the optimized conditions of pyrolysis temperature of 600 degrees C and a vacuum degree of 1000 Pa, and the recovery rate of cathode active powder reached 98.04%. In the temperature range of 450-650 degrees C, with the increase of pyrolysis temperature, the XRD patterns of the cathode active powder showed that the characteristic peak of Li[NixCoyMn1-x-y]O-2 gradually weakened and eventually disappeared.