In order to investigate the dynamic mechanical characteristics and failure mechanism of sandstone under impact loads, the dynamic mechanical tests of sandstone were carried out by SHPB device. And the stress-strain curve, dynamic compressive strength, dynamic elastic modulus and change of absorbed energy per unit volume of sandstone were studied. In this investigation, the failure mechanism was analyzed, the failure mode and the change law of failure fragmentation of sandstone were elucidated as well. The results show that the stress-strain curve of sandstone under impact loads develops in stages, with the linear elastic rising stage, nonlinear oscillation fluctuation stage and post-peak decline in order The dynamic compressive strength, absorbed energy per unit volume and dynamic elastic modulus of sandstone are related to the impact velocity by power functions, quadratic functions and quadratic functions respectively, all of which have obvious impact velocity effect. With the increases of impact loads, the fractal dimension and fracture degree of sandstone rises and the failure mode of sandstone changes from tensile failure to tensile-shear coupled failure. The results of the study can provide a theoretical basis for the stability control of the strong dynamic pressure roadway and the surrounding rock of the stope.