A solid-state mechanochemical processing, that is, pan-milling, was used to conduct the esterification of poly(vinyl alcohol) (PVA) with maleic anhydride (MA) through stress-induced reaction. FTIR spectrum study indicated the presence of ester linkages and olefinic double bonds in maleic anhydride cross-linked PVA. Thermal properties of the cross-linked product were characterized by DSC. The results showed its glass transition temperature was 20 ℃ higher than the original linear PVA and the thermal stability was also improved.