Dynamic mechanical performance experiments are carried out for red-sandstone specimens in different low temperatures under impact loading，by using the f 100 mm split Hopkinson pressure bar(SHPB) with a low temperature compensation device. Then，the scanning electron microscope(SEM) is carried out to study its microcosmic character of failure surface，and dynamic compression failure rules of red sandstone are acquired by the quantitative processing of fracture network. The results indicate that，the peak stress of red sandstone increases with the increase of strain rate，and the peak stress increases with the decrease of temperature. The strengthening effect of strain rate and the hardening effect of low temperature are obvious. In low strain rate，the primary modes of failure surface are cementing material fracture and brittle fracture，with the low energy-consuming. In high strain rate，with the former fracture modes，the surface partially appears ductile damage，while the grade of energy-consuming is pretty high. The quantitatively analysis of fracture network come to the change rules of the pore number，the plane porosity and the pore′s shape factor. With the combination of experimental results and probability theory，the dynamic failure mechanism of frozen rock is illustrated from a new perspective. The research results have important significance to the theoretical study and engineering practice of the rock mass in cold regions.