The activity of Au catalyst supported by activated carbon (Au/AC) for decomposition of low-level ozone was evaluated. The influence of preparation conditions such as pH value of precursor solution, drying mode and calcining temperature on the catalytic activity was studied, and the ozone removal ratio was tested under different space velocity at ambient temperature. The results show that the procedure of controlling the precursor pH=10, drying catalysts by microwave and being reduced at 200℃ with H2 can improve the dispersion of gold particle, decrease particle sizes and significantly enhance the activity of Au/AC for ozone decomposition. When the catalytic activity test was carried out under the condition of 50 mg/m3 ozone in air, relative humidity 45%, space velocity 72 000 h-1 and ambient temperature, the ozone removal ratio could be maintained above 90% (within 2400 min). The results of N2 adsorption-desorption and XPS show that, after the reaction with ozone the specific surface area and pore volume of Au/AC decrease slightly; Au/AC remains active although the spectrum peaks of Au4f shift toward higher. Furthermore, the fact that C content decreased notably while O increased, reveals that the Au supported on AC is concerned with the catalytic reaction and can concurrently promote another reaction between ozone and graphitic C