The preparation of polyaniline-based activated carbon by H2O(gas)-CO2 co-activation has been successfully applied to the preparation of commercial activated carbon. Compared with the chemical activation method, the product prepared by this physical activation method has no residue of activator, and the cleaning and environmental friendly. In this work, we used the polyaniline as the raw material, and explored the effect of the amount of H2O(gas) and the partial pressure of CO2 on the activated product. The pore size distribution and space structure of activated carbon were studied by means of N2 adsorption and desorption, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrochemical performance of activated carbon as electrode materials of ionic liquid capacitor was studied by electrochemical workstation. When the mass ratio of H2O(gas) to the carbonized product is 4∶1, the partial pressure of the CO2 is 0.6, the specific surface area and the pore volume of activated carbon reaches 2357 m2·g-1 and 1.45 cm3·g-1, respectively. In addition, the sample has a mesopores and macropores-rich structure, and the ratio of the mesopore specific surface area to the total specific surface area is about 40%. In ionic liquid electrolyte, the activated carbon used as electrode material of super capacitor has a high capacitance of 203 F·g-1 at the current density of 0.1 A·g-1, and has a capacitance retention of 91% after 10 000 cycles (5 A·g-1), which shows excellent rate performance and good cycle stability. When the organic electrolyte was used, the capacitance of sample is 134 F·g-1 at the current density of 1 A·g-1, and the capacitance retention is 100% at the current density of 10 A·g-1. The excellent electrochemical performance of activated carbon in the ionic liquid electrolyte and organic electrolyte is due to the unique mesopores and macroporesrich structure, which greatly reduces the ion transport resistance, thus improving the rate performance and cycle stability in ionic liquid electrolyte.