In order to study the feasibility of basalt fiber (BF) mortar applied to support in complex underground environment, four kinds of BF mortar with different contents (0, 0.2%, 0.4%, 0.6%) were prepared before testing. The dynamic compressive strength was tested by Φ74mm variable cross-section split Hopkinson pressure bar (SHPB) device. The static uniaxial compressive strength was tested by universal testing machine. The dynamic mechanical properties of BF mortar were studied by comparing the dynamic compressive strength, ultimate toughness, peak strain and dynamic growth factor. The results show that the cement mortar with BF has good impact resistance. The peak stress, ultimate toughness, peak strain and dynamic growth factor of mortar are improved with the increase of BF content. When the BF content is 0.6%, the BF cement mortar has highest peak stress at the same strain rate, and the peak strain increases by 19.26% at 80s-1 strain rate. After 65s-1, the BF cement mortar has highest ultimate toughness and the dynamic growth factor. The more the BF content, the larger the particle size of the fragments formed after mortar impact. Scanning electron microscope (SEM) analysis and damage morphology showed that BF could form a good restraint effect in cement mortar.