In this paper, Nafion membrane was firstly modified by copper phthalocyanine tetrasulfonic acid tetrasodium salt (CuTSPc) to prepare the Nafion/CuTSPc-x composite membranes. FTIR, XRD and SEM results revealed the successful incorporation of CuTSPc into Nafion and good compatibility between the two composites. The proton conductivities of the Nafion/CuTSPc-x composite membranes were evidently higher than pure cast Nafion membrane, and increased with CuTSPc contents. Among them, the Nafion/CuTSPc-6% membrane with the highest ion exchange capacity (1.14 mequiv•g⁻¹) exhibited the highest proton conductivity of 0.084 S cm⁻¹ at 30 ℃ and 0.131 S cm⁻¹ at 80 ℃, respectively. When fabricated of a membrane electrode assembly (MEA), the Nafion/CuTSPc-4.5% membrane displayed an initial fuel cell performance with a power density of 43.3 mW cm⁻² at room temperature, close to that for pure cast Nafion membrane. Benefiting from the compact structure, high proton conductivity and outstanding stability, the Nafion/CuTSPc-x composite membranes show promising potentials for fuel cell applications.