For improving the performance of acorn starch (AS) based bio-adhesive, AS graft glycidyl methacrylate (AS-g-GMA) adhesive was prepared in this paper. The properties of the AS-g-GMA adhesive were studied by Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) measurement. The bonding strength of the plywood bonded by AS-g-GMA adhesive was measured according to Chinese National Standards methods to evaluate its water resistant. FTIR results indicated that GMA was grafted on the AS successfully. The bonding strength of the plywood bonded by AS-g-GMA adhesive showed lower curing temperature, better bonding strength, and water resistance comparing with that of control. The water resistant could reach type II grade (63°C water bath 3h) plywood requirement when the glycidyl methacrylate adding amount was 6% based on AS.