1IntroductionUnsaturated polyester resins are well known as commercially available polymeric materials with numerous applications. They are used in a wide range of products, for example coating materials, structural parts of automobiles, building materials and engineering materials etc[1]. Unfortunately, these resins contain ester groups in their chain, which have high sensitivity to hydrolysis. In order to improve the mechanical properties and thermal stability of UP, in our work, the modification of UP with glass fiber and TLCP with the group of -NCO synthesized by ourselves was studied systematically. The TLCP will crosslink with UP because of the reaction between the -NCO group in TLCP and double bonds in UP initiated by curing agent.