Differential shrinkage composite yarn and preparation method thereof

The invention provides a differential shrinkage composite yarn and a preparation method thereof. The differential shrinkage composite yarn is prepared by one-step spinning of POY and FDY through 24-head winding; the differential shrinkage composite yarn comprises a core yarn and a down yarn, wherein the core yarn is FDY prepared from FDY polyester; the down yarn is POY prepared from polyester POY;the differential shrinkage composite yarn has a breaking strength of 2.1-2.4 cN/dtex, elongation at break of 30-40%, oil content of 0.8-1% and the network degree of 24-40/m, and the crystallinity andthe orientation degree of the hetero-shrinkage composite yarn are different; and the degree of crystallinity and the degree of orientation of the differentia shrinkage composite yarn are different, and thus, the prepared fabric becomes soft and fluffy and has improved water absorption. POY and the FDY are prepared into the differential shrinkage composite yarn through 24-head winding, and by adjusting process conditions,