To reveal the curing reaction characteristics of polyurethane-crosslinked energetic composite slurry， this study derived the curing kinetic equations for the HTPB/IPDI system based on the evolution of characteristic functional groups monitored by in-situ ATR-FTIR spectroscopy during the curing process. The evolution of characteristic groups was monitored at 45 ℃， 50 ℃， 55 ℃， 60 ℃ and 65 ℃. Using the derived equations， kinetic curves for the slurry curing reaction were constructed， and the apparent activation energy was determined. The results indicate a two-stage curing process. The first stage corresponds to the pre-gelation period， with an apparent activation energy （E_a1） of 69.83±5.54 kJ·mol^-1. The second stage corresponds to the post-gelation curing period， with an apparent activation energy （E_a2） of 71.31±4.45 kJ·mol^-1. The apparent activation energy for the HTPB/IPDI energetic composite slurry is significantly higher than that of a homogeneous HTPB/IPDI mixture.