To evaluate the mechanical properties and promote a better understanding of failure behavior of the newly developed Zr-Nb cladding tubes during reactivity initiated accidents (RIAs), burst tests were carried out with the biaxial stress state under different pressurization rates at the temperature ranging from 293 to 623 K. The influence of pressurization rate and test temperature was characterized in this test. The pressurization rates were 0.97 GPa/s at 293K, 0.62 GPa/s at 473K, and 0.49 GPa/s at 623K for the fast pressurization test, 0.23 MPs/s for the ASTM burst test. Maximum hoop stress was respectively increased by 10.61, 9.32 and 8.26 % compared to the ASTM burst test at 293K, 473K and 623K. The burst ultimate hoop stresses (UHS) at rupture decreased while the total circumferential elongation (TCE) increased monotonically with the rise of temperature, the uniform circumferential elongation (UCE) was not significantly affect by the test temperature. All the burst tests resulted ductile ballooning failure, cracks initiated and propagated along the axial direction above the maximum hoop stress. A higher pressurization rate resulted shorter but wider crack. As the test temperature raised, the ductility increased and the propagation of the axial crack was suppressed.