The invention provides a method for recycling lithium in waste lithium battery slags through chloridizing roasting and evaporation and belongs to the field of resource recycling. The method comprisesthe following steps: uniformly mixing pulverized lithium slags with a certain quantity of metal chloride; and then, roasting mixed lithium slag and metal chloride at high temperature, and transferringlithium in the lithium slags into a gas-phase removing system in the form of lithium chloride. The problem that the lithium in the waste lithium batteries is difficult to recycle by thermometallurgytreatment is solved. The molar ratio of chlorine in the metal chloride and the lithium in the lithium slags is 1: 1 to 2:1, and the roasting temperature is 800-1200DEG C. The method is simple to operate, causes small pollution, and is high in economical benefit and suitable for industrial popularization.