In order to investigate the curing time of different curing agents used in casting polymer bonded explosives, Fourier transform infrared spectrometer, rotary rheometer and Shore A hardness tester were used to investigate the effects of toluene diisocyanate (TDI), dimeric acid diisocyanate (DDI) and TDI/DDI mixed curing agent on curing rate, pot life and curing time of pouring PBX slurry. The results show that the reaction rate of HTPB with different curing agents at 55 ℃ is k_TDI > k_TDI/DDI > k_DDI, and the reaction follows the second-order reaction rule. For cast PBX slurry with high solid content, at a curing ratio of 1.2 and curing temperature of 55 ℃, using TDI curing agent, suitable pot life was 4 hours, curing time was 72 hours; Using DDI curing agent, pot life can reach more than 5 hours, but its curing time was 128 hours. Using TDI/DDI mixed curing agent, curing time is 96 hours, pot life can reach more than 5 hours, curing effect is more ideal.