Polymethyl Methacrylate (PMMA) has become a key material for pressure-resistant shells of full-view manned submersibles due to its high transparency, light weight and excellent pressure resistance. However, the viscoelastic creep behavior of PMMA material itself has a significant impact on the long-term reliability of the structure. Therefore, the creep buckling mechanism of PMMA pressure spherical shells and their remaining ultimate load carrying capacity were investigated based on the viscoelastic properties of PMMA. Firstly, the non-linear influence law of stress level and time on the creep behavior of PMMA was revealed through creep tensile tests. Based on short-term test data, creep curves applicable to different stress levels were obtained by applying the time-stress equivalence principle while the applicability of the Burgers model and the modified Burgers model was discussed and analyzed. Subsequently, based on the modified Burgers model and numerical simulations, the influence of key factors, like initial geometric defects, the thickness-to-diameter ratio and working depth on the residual ultimate load of spherical shells after different creep durations was analyzed. The research results can provide certain theoretical basis and data support for the design, safety assessment and life prediction of full-view PMMA pressure-resistant structures.