Due to the complexity of the experiment, the research on the dynamic mechanical properties of concrete under complex stress conditions after high temperature has been less, but in building fires and defense and military protection projects, concrete structures are mostly under the combined action of multiaxial stress and impact loads. In order to study the biaxial dynamic mechanical properties of concrete after high temperature under combined static and dynamic loads, a true triaxial static and dynamic comprehensive loading experimental system is used. A true triaxial test machine is used to apply biaxial axial pressure in advance, and the SHPB test device is used to apply dynamic load to concrete specimens after atmospheric temperature (25 ℃) and 200, 400, 600, 800 ℃ high-temperature, respectively, finding the regularity of the dynamic mechanical properties of concrete under the biaxial stress state after high temperature. The test results show that: temperature change is the main influencing factor of the biaxial dynamic mechanical properties of concrete after high temperature, and strain rate change is the secondary factor; when the temperature is higher than 400 ℃, the stress-strain relationship curve shows a yielding platform, and the concrete toughness is significantly improved than under low temperature. 200 ℃ is the transition temperature of biaxial dynamic compressive strength of concrete after high temperature. When the temperature continues to increase, the biaxial dynamic compressive strength decreases significantly.