The invention relates to a differential-shrinkage cotton-like composite filament and preparation method thereof; the differential-shrinkage cotton-like composite filament is a composite filament blended by a modified
polyester POY filament and a modified
polyester FDY filament; the modified
polyester consists of polyester and aminoadipic acid glycol ester; the aminoadipic acid glycol ester is dispersed among the molecular chains of the polyester; and the aminoadipic acid glycol ester takes effect of
hydrogen bond among the molecular chains of the polyester, so as to stabilize the positions of the aminoadipic acid glycol ester with respect to the molecular chains of the polyester; in condition of the temperature is 90-130 degrees centigrade, the free volume spaces among the molecular chains inside the
fiber of the differential-shrinkage cotton-like composite filament are increased by 20-30v / v%. The aliphatic ester increases the free volume of the polyester
fiber in order to increase the
diffusion degree of the dye, thereby increasing the
dyeing performance of the polyester
fiber. The differential-shrinkage cotton-like composite filament is applicable to clothes fabric,
bedding article, decoration article, and the like.