Blend films have been prepared from a mixture of high molecular weight polyacrylic acid (PAA) and polyvinyl alcohol (PVA). The PAA/PVA blend films were crosslinked through heat treatment. The effects of varying the molecular weight and content of PAA on the water resistance of the resulting films were investigated, and the retention ratio of the PAA/PVA blend films was studied in boiling water. The results showed that the boiling water resistance increased as the molecular weight and the content of PAA were increased. The optimum heat treatment temperature was found to be in the range 160-180℃， and the optimum heating time in the range 3-15min. The maximum observed T_g value of the blend films after heat treatment was 102℃, which represents an expansion of the temperature range in which blend films can be used.