The research on the properties of epoxy asphalt mastic is very important due to its performance being closely related to that of epoxy asphalt mixture. This study evaluates the viscosity evolution, tensile properties, high temperature stability, low temperature crack resistance, and fatigue resistance of epoxy asphalt mastic at varying filler to asphalt ratios (F/A), and compare its performance to those of matrix asphalt mastic and SBS asphalt mastic. Besides, the surface morphology of epoxy asphalt mastic is observed through a stereo microscopy. The results show that as the F/A increases, the viscosity of epoxy asphalt mastic increases; the tensile strength increases, while the elongation at break decreases; high temperature stability first increases followed by a decrease, with optimal performance at the F/A range of 0.8–1.4; fatigue resistance first increases followed by a decrease as well, with optimal performance at the F/A range of 0.6–1.2; the rigidity increases at low temperature, but the crack resistance decreases. The optimal F/A range for best overall performance is determined as 0.8–1.2. Compared with matrix asphalt mastic and styrene-butadiene-styrene (SBS) asphalt mastic, epoxy asphalt mastic shows excellent stability at high temperature and fatigue resistance under low applied strain, except that the crack resistance of it at low temperature becomes less sensitive to changes in limestone fillers content when the F/A is greater than 0.6. Stereo microscopic imaging reveals that limestone fillers evenly disperse in epoxy asphalt at low F/A, with agglomeration occurring when F/A exceeds 1.8. This study highlights the unique performance advantages of epoxy asphalt mastic, and provides essential insights into application of epoxy asphalt mastic in pavement engineering.