The invention relates to a 
copolyester melt direct-
spinning controllable multiple differential shrinkage composite 
fiber and a preparation method thereof. 
Terephthalic acid and 
ethylene glycol serve as raw materials, a third component of 
polyethylene glycol, a fourth component of 
diethylene glycol and a fifth component of 
pentaerythritol are added for copolymerization, a 
copolyester melt is prepared, pressurized through a melt pipeline and a pressurizing pump, conveyed to a 
spinning box, divided into two ways through two metering pumps, sent into a 
spinning assembly and a spinneret plate for 
extrusion and cooled and solidified to form two bundles of 
yarn, FDY (fully drawn 
yarn) is obtained after oiling wheel oiling, pre-interlacing, drawing and 
heat setting of one of the two bundles of 
yarn, the other bundle of yarn is oiled through an oil spraying 
nozzle and then led to two yarn guiding disks to obtain POY (
polyester pre-oriented yarn), the FDY and the POY are input into a yarn doubling device and a main interlacing device simultaneously for composition, and the composite 
fiber is obtained after ultra-high-speed winding molding. The composite 
fiber adopts the better fine three-dimensional multi-layer structure and is large in potential controllable hot-
shrinkage rate difference, good in fluffiness, hygroscopicity, air permeability, 
moisture retention, 
chromaticity and 
high color rendering uniformity, multiple in 
product function and high in additional value.