A new kind of thermal regulating fiber based on polyvinyl alcohol (PVA) and paraffin was prepared by wet composite spinning. In this fiber, PVA was the matrix or "sea" polymer to support the "island" paraffin, which was selected as phase change materials (PCMs) to store energy. Because of PVA's excellent barrier ability to nonpolar substances, paraffin can be remained in fiber stably. The thermal stabilities of fibers, thermal treating effects on fibers, mechanical properties of fibers, morphology and thermal properties of fibers were investigated by tensile strength tester, DSC and TGA. Results show that the thermal regulating fiber has the acceptable thermal stability when the content of paraffin in fiber was less than 30%. The best fiber properties of tensile strength 2.6 cN/dtex, breakage elongation: 19.9%, latent heat: 24.45 J/g can be achieved by manipulating the preparation process, and the latent heat of the fiber still remains 24.32 J/g after 25 times washing. (C) 2008 Elsevier B.V. All rights reserved.