To explore the damage evolution behavior of polymer bonded explosive (PBX) under uniaxial compression, the in-situ investigation of PBX substitute material in the uniaxial compression process was carried out by computed tomography (CT).In-situ CT images of the specimen under different loads were obtained.The mean gray value variations of the specimen in loading process were obtained through analyzing the gray value of CT images.Internal three-dimensional displacement field and strain field of the specimen were obtained using the digital volume correlation (DVC) method.Combined with the digital image correlation (DIC) method and the gray analysis of the specimen surface, the strain distribution and surface crack growth process of PBX substitute material in loading process were clarified.Results show that at the initial loading stage before the damage occurred, the mean gray value of CT image is almost constant.With the increase of load, the micro-damage may occur inside the specimen and the mean gray value of CT image decreases slightly.At the later loading stage, the damage accumulates rapidly and the mean gray value of CT images decreases sharply.The mean gray value of CT image can be considered as an important index to reveal the micro-damage change of material with resolution higher than CT technique, and internal strain field of the specimen and change of the surface gray value can be used to characterize the accumulation process of material damage during loading.