[Purposes] This paper aims to study the rheological and fatigue properties of graphene nanoplatelets (GNPs) and SiO₂ composite modified asphalt. [Methods] The preparation of GNPs and SiO₂ composite modifiers using the mechanical ball milling method was studied. Different amounts of ball-milled GNPs/SiO₂ composite modifiers were selected. The high-temperature rheological and fatigue properties of ball-milled GNPs/SiO₂ composite modified asphalt were analyzed through the multiple stress creep recovery (MSCR) test, temperature scanning test, frequency scanning test, and linear amplitude scanning test, revealing the mechanism of ball-milled GNPs/SiO₂ composite modification. [Findings] The addition of ball-milled GNPs/SiO₂ composite modifiers can significantly improve the deformation resistance of modified asphalt under repeated loading at high stress levels. When the amount of composite modifiers reaches 9‰, the deformation resistance of ball-milled GNPs/SiO₂ modified asphalt is significantly improved. At low strain levels, the addition of ball-milled GNPs/SiO₂ composite modifiers is beneficial for improving the fatigue resistance of asphalt. [Conclusions] Compared with single modified asphalt, ball-milled GNPs/SiO₂ composite modified asphalt has better deformation resistance under repeated loading at high stress levels and fatigue resistance at low strain levels.