According to the problem of reflection crack in the retrofitting project of old cement pavement in hot and humid area of South China, a dual fiber reinforced asphalt mixture that can be used for anti-crack interlayer or overlay structure layer was designed. Through high temperature penetration test, low temperature bending test, freeze-thaw splitting test, the semi-circular bending test(SCB), the indirect tensile cracking test (IDEAL-CT) and semi-circular bending crack extension test, the high temperature performance and low temperature performance, water stability and fatigue cracking resistance of dual fiber reinforced asphalt were analyzed. Based on the extended finite element method (X-FEM) and improved Paris formula, the crack fatigue extension finite element model under traffic load was established to analyze the anti-cracking effect of dual fiber reinforced asphalt mixture. The findings indicated that in the context of southern climates characterized by high temperatures and humidity, the incorporation of a 1∶1 ratio of lignin and basalt fibers into asphalt mixtures resulted in enhanced high-temperature deformation resistance and water stability. The penetration strength was 1.27 MPa, the maximum bending and tensile strain was 3 596.3 μɛ, the residual stability was 94.1%, and the freezing and thawing cleavage strength ratio was 96.2%. Furthermore, the material exhibits excellent anti-cracking properties, with a fatigue life of 30 503 cycles (0.2 stress ratio), the cracking energy was 5 343.9 J/m², and the flexibility index was 22.82. In regions with low temperatures, the use of a dual-fiber reinforced asphalt mixture, comprising a lignin fiber to basalt fiber ratio of 1∶3, was recommended to enhance low-temperature performance. Dual fiber reinforced asphalt mixtures are more effective against reflective cracking when treating old concrete pavements until the joint load transfer coefficient of the old concrete pavement is increased to 80%.