The invention discloses a multi-component yarn. The multi-component yarn comprises the following components in percentage by weight: 15 to 45 percent of polyterephthalate-1,3-propylene glycol ester fiber, 15 to 45 percent of polylactic acid fiber and 15 to 45 percent of viscose. The multi-component yarn has high moisture absorption, air permeability, elasticity, fluffy and soft handfeel, high comfortability when contacting with skin, bright color and rich luster in cloth and excellent heat resistance and ultraviolet resistance, is easy to dye, and can be widely applied to textiles, in particular to the textiles for clothes. The invention also discloses a method for preparing the multi-component yarn. By the method, the conventional spinning equipment is fully utilized and a spinning machine does not need to be researched singly, so the spinning difficulty is reduced, the product quality is improved and the method is suitable for industrialized production.