To improve the serviceability and extend the service life of steel bridge deck pavement (SBDP), a high-performance polymer mixture (HPPM) with high content polyurethane binder and great impermeability was proposed as the protective course of SBDP, and its feasibility as the protective course of SBDP was evaluated comprehensively from different perspectives. Firstly, the material characteristics of HPPM were evaluated through various mixture tests. Afterwards, the cooperative performances of this protective course were assessed through some designed composite structure tests. Finally, the structural performance of HPPM was investigated through the finite element model. Meanwhile, the widely used SBDP protective course materials were also tested for comparison study. Results show that the HPPM has high compressive strength, great cracking resistance and superior deformation compliance. It can improve the stability and cooperative deformation performance, and the reasonable distribution of stress for the composite SBDP structure. It could be a good material used as the protective course of SBDP.