The objective of this study is to examine the impact of silane coupling agents on the performance of asphalt mastic when used in conjunction with basalt fibres. To achieve this, a series of experiments have been conducted, including taper penetration, bending beam rheology and dynamic shear tests. These experiments have been designed to assess the effect of varying dosages of modified basalt fibres on the rheological properties of the asphalt mastic. The objective of this study was to examine the impact of coupling modified basalt fibres on the rheological properties, high temperature stability, and low temperature cracking resistance of asphalt mastic at varying temperatures and dosages. The findings indicate that the shear strength and consistency of the asphalt mastic can be enhanced through the incorporation of these fibres. Following modification, the phase angle decreases, and the asphalt mastic exhibits greater elasticity and thus a larger complex modulus. The coupling of modified basalt fibres can enhance the high-temperature deformation resistance and low-temperature crack resistance of asphalt by increasing the adsorption effect with asphalt. The optimal fibre dosage of the modified fibres is approximately 2.6%. In conclusion, the coupling of modified basalt fibres can yield superior rheological properties.