Tensile mechanical properties of some PBXs were evaluated by Flattened Brazilian Disc (FBD) and Split Hopkinson Press Bar (SHPB). Quartz transducers and digital image correlation（DIC) technology were used to measure stress and strain information. Stress-strain curves of three types of PBXs under strain rate of 10² s^-1 were obtained. Results show that all of the tensile strength, failure strain and dynamic modulus have relationship with the loading strain rate. A constitutive model had been established based on the experimental data.