The reaction kinetics of the GAP/HMDI, GAP/TDI and GAP/IPDI (where GAP, HMDI, TDI and IPDI are glycidyl azide polymer, hexamethylene diisocyanate, toluene diisocynate and isophorone diisocyanate)systems in the presence of dibutyltin dilaurates (T12)was studied by variable temperature FTIR spectrum method. Results show that the reactions of GAP and three kinds of isocyanates (HMDI, TDI and IPDI) are of the second order. Their reaction rates rise with increasing the reaction temperature. The values of activation energy for reactions of the GAP/HMDI, GAP/TDI and GAP/IPDI systems are 15.49, 12.27, 22.46 J·mol^-1, respectively, revealing that the reaction activity of three systems decreases in the order of GAP-TDI>GAP-HMDI>GAP-IPDI.