The preparation of hydrophilic microfiltration membranes by a sacrificial layer via co-casting is reported in this paper. The membranes were fabricated using two polymer solutions. Selection of the sacrificial coating layer was based on solution blending between coating solution/PSf solution and co-casting of two solutions. Based on delamination guideline, PEI was selected as the sacrificial layer for the investigation on PSf membrane structure. PSf membranes prepared as such showed improved permeability and surface porosity. Concave structure was observed in PSf membrane surface, hypothetically caused by the growth of macrovoids in PEI layer during phase separation.