Abstract: Objective: To prepare polymer-polyvinyl alcohol(PVA)and polyacrylamide(PAM) hydrogel used for oral soft tissue expansion. Methods: PVA and PAM were dissolvedat a high temperature and frozen in a low temperature and then melted at room temperature. After being dried in the vacuum oven ,and cut into cubes which were 18 mm*5 mm*4 mm in volumewith the concentration of15wt%,20wt% and 25wt% respectively. The dry gel of PVA and PAM were characterized. Results: The dry gel of PVA was hard, homogeneous and smooth on the surface. But the dry gel of PAM could be found small holes on the surface and was fragile, uneven and rough. Conclusion: A small amount of PVA and PAM could be dissolved in deionized water through stirring at room temperature, but PVA and PAM could be completely dissolved at a higher temperature. PVA could be solidified through repeated freezing and unfreezing for several times, and become dry gel by vacuum drying , which woud be shrunken two or three times in the volume.