In order to evaluate the effect of damp-heat aging on the properties of pentaerythritol acrolein resin （123 resin）-RDX polymer， experimental study on accelerated aging by dampness and heat was carried out. The moisture absorption properties of pouring PBX explosive specimens， mechanical properties before and after moist heat aging， section morphology and aging mechanism were analyzed by means of water adsorption instrument， material testing machine， scanning electron microscope and infrared spectrum. The results showed that the moisture absorption rate of RDX， 123 resins and pouring PBX increases with the increase of relative humidity. Among them 123 resins has the highest moisture absorption rate. Relative to the main explosive RDX has stronger hygroscopic property. The results show that the moisture absorption of pouring PBX is dominated by 123 resins in the system. The results of infrared spectrum showed that 123 resins had hygroscopic hydrolysis after heat and hunmidity aging， Meanwhile， moisture and heat aging significantly affected the mechanical properties of 123 resins-based casting PBX. The mechanical properties of 123 resin based cast PBX decreased significantly with the increase of ambient humidity， and the mechanical properties decreased obviously with the extension of aging time.. After aging at 65 ℃/90% RH for 5 days， the compressive strength decreased by 17.60 MPa（24.09%）， the tensile strength decreased by 2.32 MPa（28.78%）， when aging for 30 days， the compressive strength decreased by 77.80% and the tensile strength decreased by 58.56%； The results showed that 123 resins based casting PBX was sensitive to humidity， and the hydroscopic hydrolysis of 123 resins was the main reason for the significant decrease of the mechanical properties of casting PBX.