The preparation of novel membranes based on cellulose acetate and polymethylmethacrylate blends in the absence and presence of the pore former by solution blending and ultrafiltration set up was carried out. The effect of compaction time on pure water flux at higher transmembrane pressure for various polymer compositions of the above blends both in the presence and absence of the pore former PEG 600 at different concentrations were reported for individual polymer blends. The pure water flux at 345kPa, Molecular weight cut-off (MWCO). The application of the characterized CA/PMMA blend membranes for the separation of proteins such as Bovine Serum albumin, Egg Albumin, Pepsin, and Trypsin, and toxic heavy metals such as Cu(II), Ni(II), and Zn(II) using polyethyleneimine as complexing agent have been attempted and the results indicate the efficiency of the ultrafiltration blend membranes.