A new type of cross-linked polymer blend membranes consisting of poly(vinyl alcohol) (PVA), sulfosuccinic acid (SSA) and plasticizer polyethylene glycol (PEG) have been prepared and evaluated as proton-conducting polymer electrolytes. The proton conductivity (σH+) and water uptake (WU) of the membranes were investigated based on such points of view as thermal cross-linking and chemical cross-linking procedure, plasticizer effect and the content of SSA. It is found that the proton-conductivity increased with increasing the content of SSA and, reached up to 0.047 S cm -1 at room temperature with a polymer composition PVA/SSA being 1:0.5 by mass. The cross-linking modification and plasticizer addition also played an important role in σH+ and WU. The membranes were characterized by thermogravimetric analysis (TGA), and the TG results showed that the thermal stability of the resultant membranes are improved due to the chemical crosslinking and plasticizer modifications.