The invention discloses a method for preparing optothermal responding short fiber by using recycled polyester bottle chips and belongs to the field of chemical fiber production. The method comprises the steps of drying optothermal responding masterbatch and recycled polyester bottle chips, mixing, carrying out screw melt extrusion on a mixture to obtain a melt, and performing filtering, melt spinning, cool-forming, coiling and oiling, drafting and feeding, receiving and barrel charging, bundling, drafting, oiling, yarn pilling, coiling, thermal setting and cutting to obtain the optothermal responding short fiber. The optothermal responding short fiber is prepared through optothermal responding masterbatch and recycled polyester bottle chip mixing and melt spinning, the preparation method is reasonable, highly operable and easy to industrially implement, the prepared optothermal responding short fiber is used mainly in textile products such as automobile trims, casement fabric and decorative fabric and has the excellent functions such as near-infrared and visible light absorption, heat accumulation and discharge, and temperature adjustment.