［Objective］ To explore the potential application of piperazine as a low-toxic andbiodegradable post-extension agent in the development of high-performance environmentally friendlypolyurethane materials.［Methods］ Waterborne polyurethane（WPU） emulsions with different piperazine contents were prepared by post-extension technology using polycarbonate diol（PCDL）， isophorone diisocyanate（IPDI）and piperazine as the main raw materials. The effects of piperazine onthe properties of emulsions and the mechanical properties，hydrophobicity and thermal stability of films were systematically study.［Results］The introduction of piperazine significantly optimized the material properties：with the increase of piperazine content，the particle size of WPU emulsions gradually decreased，the viscosity gradually increased；the water contact angle gradually increased；the tensile strength could reach up to 19. 42 MPa，and the elongation at break could reach up to 909. 81%. ［Conclusion］ As a low-toxic，biodegradable post-chain extender，piperazine enhances its environmental friendliness while maintaining the coating's good mechanical properties and heat resistance，providing theoretical basis and technical support for the development of high-performanceenvironmentally friendly polyurethane materials.