High-performance polysulfone (PSf)/poly (4-vinylpyridine) (4-PVP)/silicon rubber (SR) multilayer composite membranes were developed for CO2/CH4 separation. PSf hollow-fiber substrates with different pore sizes were manufactured by varying the concentration of nonsolvent additive in the spinning dope. PSf/4-PVP/SR multilayer composite membranes were prepared using dip-coating. The pore size of the PSf substrate increased with an increase of the nonsolvent additive. Selectivity of a composite membrane for CO2/CH4 increased with decreasing pore size of the substrate. The pre-wetting agent played an important role in preventing the penetration of the coating material into the substrate with large pores, but did not show a significant effect on a substrate with small pores. A high-performance multilayer composite membrane with a CO2/CH4 selectivity of 29 and CO2 permeance of 92 GPU was obtained.