The anti cracking performance of the asphalt mortar with 0% and 03% basalt fibers was compared through semi circular bending test and scanning electron microscope(SEM) analysis. The result shows that adding appropriate amount of basalt fibers can enhance the mechanical performance, for the specimens without notch the max load increases by 162% and the critical cohesion increases by 143% and for the specimens with notch the max load increases by 512% and the critical fracture energy increases by 172%; Basalt fibers can also raise the viscosity of asphalt mortar, suppress the flowability of the asphalt and it is well compatible with asphalt, so the adhesion is enhanced. This is why basalt fibers can decrease the cracking probability.