The invention relates to homogeneous hyper-viscous 
polyester and a preparation method thereof. The method comprises the following steps of: controlling the mechanism of adding a catalyst during a synthesis process to obtain low-viscous 
polyester with an 
intrinsic viscosity of 0.300-0.500 dL / g, and then performing 
solid phase thickening on the low-viscous 
polyester to obtain the homogeneous hyper-viscous polyester with an 
intrinsic viscosity of 0.85-1. 15dL / g, an 
intrinsic viscosity deviation less than or equal to 0.02dL / g and a molecular 
weight distribution index of 2.5, wherein the catalyst is added when the average 
polymerization degree of an 
intermediate product in a 
polymerization reaction reaches 8-17; the pre-reaction of the 
solid-phase thickening is divided into four stages which are a first stage, a second stage, a third stage, and a fourth stage, the corresponding temperatures are 190-195 DEG C,195-210 DEG C, 210-220 DEG C and 220-230 DEG C respectively. The preparation methodof the homogeneous hyper-viscous polyester obviously reduces the content of 
oligomer in a product, and the prepared polyester has high quality and excellent popularization value.