Sulfur-containing diol ME-HEA was synthesized from 2-mercaptoethanol (2-ME) and hydroxyethyl acrylate (HEA) by a thiol-ene click reaction. Further, it was used as a chain extender to prepare a series of sulfur-containing waterborne polyurethane (SWPU) emulsions using polyoxypropylene diol (PPG) and isophoronediisocyanate (IPDI) as raw materials. The particle size of the emulsion, the thermal properties, mechanical properties and water resistance of the films were tested by nanometer particle size analyzer, infrared spectrum and electronic tensile machine. The results show that with the increase of ME-HEA content, the heat resistance and mechanical properties of SWPU film obviously improve. When the content of ME-HEA was 4.3%, the particle size of the emulsion was 41.7 nm, the tensile strength and elongation at break of the film were 34.3 MPa and 911.2%, respectively. After the film was treated by thermal oxygen degradation at 120℃, its tensile strength was 90.09% of that before treatment, indicating that the film had a good thermal decomposition resistance.