The invention discloses a regeneration method of chloroaluminate ionic liquid. The regeneration method comprises the following steps: adding a proper quantity of molecular sieves into the ionic liquid needing to be regenerated, then adding a proper amount of anhydrous AlCl3 under the condition of ice-water bath, stirring for reaction, heating for reaction, cooling, and performing solid-liquid separation to obtain the regenerated chloroaluminate ionic liquid. The regeneration method disclosed by the invention has the advantages that since water has critical influence on the catalytic activity of the chloroaluminate ionic liquid, the molecular sieves and the anhydrous AlCl3 are added simultaneously, and the adding quantities, the reaction temperature and the reaction time of the molecular sieves and the anhydrous AlCl3 are optimized, so that water is removed in an effective manner, the loss of the ionic liquid is little, the activity of the ionic liquid can be effectively restored, the catalytic efficiency and the recyclable frequency of the ionic liquid can be increased, and further, the yield of synthesized phenylcyclohexane catalyzed by the regenerated ionic liquid is increased.