Abstract: Starchbased aqueous polymer isocyanate adhesive was used to bond the structural laminated lumber. Then it was retrogressed accelerative by boiling treatment. The chemical and physical changes in the aging process were analyzed by means of Raman, 13C-NMR and GPC to reveal the retrogress mechanism. The results showed that the reaction of -NCO group occurred in the bonding film in the process of retrogress, i.e., the amine compounded firstly and then decompounded. But there was no change in the modified starch linked to the polymer isocyanate (PMDI). After the accelerated retrogression, the chains of polyvinyl alcohol (PVA) in the adhesive were cut into small molecules dissolving in water. Other components did not dissolve or degrade.