The invention discloses a method for extracting lithium from carbonate clay type lithium ore by using an ion exchange method, and belongs to the technical field of lithium extraction. According to themethod, a molysite is used as an extracting agent to carry out ion exchange reaction with the ore to leach the lithium into a solution. The method specifically comprises the following steps: crushingand grinding the clay type lithium ore, carrying out high-temperature roasting activation, and then carrying out ion exchange reaction by using an iron salt solution under a heating condition; and carrying out solid-liquid separation by filtering to obtain a filtrate which is a lithium-containing solution. The extraction rate of the lithium can reach 90% or more, and meanwhile, the method has thecharacteristics of low cost, high efficiency, environment friendliness, simple process and the like; the obtained solution is close to neutral, mainly contains aluminum, a small amount of iron and other impurities, and is convenient for subsequent separation and purification; the method provides an important new approach for developing and utilizing a novel lithium resource of the carbonate claytype lithium ore.