A carbon microflake has been prepared using phenolic resin and acetate magnesium as carbon source by one-step pyrolysis method and then activated with molten KOH at 600°C for 1h in nitrogen atmosphere. As-synthesized products have been characterized by scanning electron microscopy, X-ray diffraction, Raman spectroscopy, N2 adsorption-desorption and electrochemical measurement. The characterization results indicate that carbon microflakes after the activation possess microporous structure and relatively larger specific surface area (632 m2 g-1). Raman spectra reveal the defect on its surface is increased. The gravimetric specific capacitance (186.5 F g-1) of the activated carbon microflakes is significantly improved. The high area-normalized specific capacitance (30 μF cm-2) is obtained.