In order to study thermal shock damage characteristics of small-size polymer bonded explosive （PBX） hemispheres， 0-100 ℃ water-bathed thermal shock test was carried out for Φ10 mm TATB based and HNS based PBX hemispheres. 3D morphology and distribution characteristics of the damages in the PBX hemisphere were studied by X-ray micro-computed tomography，and the thermal conduction and thermal stress of the sample during the thermal shock process were simulated and analyzed by using the 2D axisymmetric thermal elastoplastic model. The CT results show that the two kinds of samples both started to crack from hemisphere corner， in which the cracks in TATB based PBX hemisphere propagate in a circumferential direction along the edge， with tortuous shape and characteristics of tearing and brittle fracture； The cracks in HNS based PBX hemispheres basically penetrate along the axial direction， with the morphology of straight and characteristics of brittle fracture. The simulation results show that strong tensile stress is generated in the in the hemisphere of TATB based PBX during temperature. And the tensile stress from hemisphere corner to hemisphere center region successively exceeds tensile strength， resulting in the initiation of the main cracks from the edge of hemisphere and propagated inward. The damage characteristics of the sample is consistent with the stress distribution characteristics and the temperature characteristics of the binder under temperature shock. This study lays a foundation for the analysis of temperature shock damage mechanism of TATB-based and HNS-based PBX.