A polythiophene (PTh) film was successfully electrochemically polymerized onto a carbon paper substrate by a galvanostatic method in an oil-in-ionic liquids (ILs) microemulsions electrolyte. The morphology of the as-prepared PTh film was investigated by using a scanning electron microscope, and the result demonstrates that the PTh particle size is to be between 2–3μm. The FT-IR spectrum of PTh film shows that the polymerization has occurred at the 2, 5-substituted position of the thiophene ring to form α-α PTh film. Further work has also been done to investigate the potential application of the PTh film as a supercapacitor electrode material in 1mol/L Na2SO4 solution. The highest specific capacitance of 103 Fg−1 can be reached at the lowest current density of 0.3 Ag−1, and the coulombic efficiency is 91.63% when the current density is 1 Ag−1. The cycle stability based on the PTh film electrode was investigated, and the result disclose that it has a good cycle stability after 500 cycles. The work demonstrates that the feasibility of electrochemically assembling of PTh film in O/ILs micromulsions.