Chrysanthemum-like and spherical α-MnO2 particles were synthesized via a chemical co-precipitation route under acidic condition. With the as-prepared α-MnO2 as the oxidant, polyaniline (PANI)/α-MnO2 composites with different mass ratios of starting aniline to α-MnO2 have been successfully synthesized by the oxidative polymerization of aniline in H2SO4 medium. The as-synthesized PANI/α-MnO2 products were characterized by means of XRD, FT-IR and SEM. Their electrochemical properties as electrode materials for supercapacitors were investigated via cyclic voltammetry and chronopotentiometry in 1 mol/L Na2SO4 aqueous electrolyte solution. The results show that the maximum specific capacitance of the PANI/α-MnO2 composite prepared with a mass ratio of starting aniline to α-MnO2 of 1:3 is 64.58 F/g, which is 1.46 times higher than that of pure α-MnO2 when the amount of α-MnO2/PANI in the electrode is less half of that of α-MnO2. Furthermore, above 85% of the initial specific capacitance for the PANI/α-MnO2 composite can be maintained after 600 cycles, while only 57 % is obtained for α-MnO2.