With the increase of mining depth and mining intensity, the occurrence frequency of rock burst is more, the strength is larger, and the damage range is wider. Rock burst tends to occur in unstable regions with cracks, which poses a huge potential threat to mine safety production. Mastering the dynamic mechanical properties of fractured rock mass is of great significance to mine production. In order to obtain the mechanical properties of sandstone containing double flaws under dynamic loads, the impact tests under different gas pressures were carried out on double-flawed sandstone specimens by using split Hopkinson pressure bar test system. The dynamic load stress-strain curves, the failure process of specimens and the degree of damage of specimens after impact were obtained by the test. The influence of flaw angles and gas pressure on the dynamic mechanical properties of specimens is analyzed from various aspects such as compressive strength, peak strain, elastic modulus, secant modulus and other mechanical parameters. High-speed camera was used to record the crack propagation and ultimate failure mode of the specimens during the impact process of the specimen, and the sketch map was analyzed. Based on this, the influence of flaw angle and impact pressure on crack propagation and failure mode of specimen was analyzed. Finally, the sample fragments after the test were collected and processed by fractal, and the degree of fragmentation of the sample was analyzed combined with dissipation energy. The results can provide a theoretical basis for the prevention and control of rock burst disasters in flawed rock masses.