Traditional approaches to recycle and regenerate spent lithium-ion batteries by leaching are polluted and complicated. In this study, a green and simple technique has been provided to regenerate spent LiNi0.5Co0.2Mn0.3O2 cathode material, besides, the regenerated mechanisms are investigated. Studies indicate that lost lithium ions in material lattice are replenished by added lithium, meanwhile, insulting impurities on particle surface remove basically, cracked and broken particles disappear during the regeneration process. Electrochemical tests demonstrate that the performances of regenerated material improve significantly. The discharge capacities are 164.6 mAh g−1 at 0.1 C rate and 147 mAh g−1 at 1 C rate, respectively. They still could deliver a discharge capacity of 131 mAh g-1 with a high capacity retention rate of 89.12% after 100 cycles at 1 C, which can be considered as a preferable electrical energy storage system. The improved electrochemical performances prove a facial and effective regeneration process.