Abstract: A novel phase change polymer, poly(diethylene glycol hexadecyl ether acrylate) (PC16E2AC), was successfully synthesized by the free radical polymerization method. PC16E2AC with melting peak temperature at approximately 35℃, being close to the temperature of human skin, was selected as the core material to fabricate a series of core-sheath thermo-regulating fibers with various heat enthalpies via bicomponent wet-spinning technology with acrylonitrile-vinylidene chloride copolymer (P(AN-co-VDC)) being employed as sheath. The morphology, microstructure and thermal property of the composite thermo-regulated fibers were characterized systematically. The results show that the PC16E2AC-P(AN-co-VDC) composite thermo-regulated fibers have uniform diameter, smooth surface and obvious core-sheath structure. Moreover, with increasing of the core-sheath extrusion ratio (S:C), the diameter of sheath increases gradually while the diameter of core shows the opposite trend. The breaking strength of PC16E2AC-P(AN-co-VDC) composite fibers improves steadily and the enthalpy also changes from 23 J/g to 57 J/g in the meantime. The fibers have good thermal stability under 220℃. 300 times thermal cycle test and 24 hours extraction experiment in toluene shed light on the good thermal reliability and excellent anti-osmosis property of the PC16E2AC-P(AN-co-VDC) composite thermo-regulated fibers. It is noted that the melting peak temperature of the PC16E2AC-P(AN-co-VDC) composite thermo-regulated fibers always remains at about 35℃, which indicates the potential for their application in smart textiles.