The invention discloses a preparing method of cyclic regenerated high simulation imitated down fiber. The preparing method comprises the steps of 1, preparing high-viscosity regenerated polyester slices, that is, waste polyester bottle chips are adopted as a raw material to prepare the high-viscosity polyester slices; 2, preparing low-viscosity regenerated polyester slices, that is, waste polyester fabric is adopted as a raw material to prepare the low-viscosity polyester slices; 3, preparing the cyclic regenerated high simulation imitated down fiber, that is, conducting processes of windchilling, oiling, winding, bucket-falling, balancing, bundling, drafting, oiling, tension heat setting, winding, drying, cutting and packaging on the high-viscosity polyester slices and the low-viscosity polyester slices to prepare the cyclic regenerated high simulation imitated down fiber. According to the preparing method of the cyclic regenerated high simulation imitated down fiber, the regenerated polyester slices with viscosity differences are adopted as the raw materials to prepare composite staple fiber with a three-dimensional crimping structure through a double component juxtaposition compound spinning method, the preparing technology is simple, the technology controllability is high, the product additional value is high, and the method meets the requirements for textile cyclic regeneration.