Disclosed is a polyester conjugated yarn, including two types of polymers having a large intrinsic viscosity difference subjected to bi-component spinning so as to be longitudinally arranged in a side-by-side sectional structure, in which the twp types of polymers are polyethyleneterephthalate having intrinsic viscosity of 0.45-0.65 as a first polymer and polytrimethyleneterephthalate having intrinsic viscosity of 0.90-1.10 as a second polymer. The polyester conjugated yarn is advantageous in terms of superior spinnability and high uniformity index. In addition, the polyester conjugated yarn can exhibit high self-crimping properties through relaxation-heat treatment of the dyeing and finishing process, and as well, can be applied to manufacture woven/knit fabrics having softness to the touch, beautiful colors, and high drapery and bulk properties, due to inherent characteristics of polytrimentyleneterephthalate.