Abstract: To enhance the physical properties of Nitrile Butadiene Rubber (NBR) for footwear applications, this study employed amorphous calcium sulfate (CaSO₄) and calcium carbonate (CaCO₃) as hybrid fillers to reinforce and modify the NBR composites. The effects of filler ratios on the mechanical properties of NBR were systematically investigated through Mooney viscosity measurement, tensile tear strength, density, heat aging resistance, oil resistance, and abrasion resistance tests. Results demonstrated that, at a CaSO₄/CaCO₃ mass ratio of 1∶3, the NBR composite exhibited optimal tear strength of 15.39 kN/m, and its density achieved 1.42 g/cm³ with the increasing of CaSO₄/CaCO₃ proportion. Notably, the composite displayed excellent thermal oxidative aging resistance. Further evaluation revealed an abrasion volume of 0.78 cm³ of the NBR composite for its shoe sole applications at this filler ratio, along with a post-oil-resistance-test volume swelling rate below 15%, confirming its superior oil resistance. This research provides both methodological frameworks and foundational datasets for the performance optimization of the NBR-based shoe sole materials.