A method for purifying polluted air in large open space was proposed and verified based on concentration gradient diffusion theory and relative motion principle of purifying device to polluted air. As to the sources of particle emitting, the purifying device works as a sink no matter it is moving or not. Both indoor and outdoor experiments have been made. In the indoor experiment, severe haze environment was simulated by fuming. The purifying device was made of metal wire and carbon cloth. The fixed device took 2.7, 6.2 and 13 minutes to reduce the particle concentration in the 7 m farthest corner of the laboratory to 50%, 20% and 0 respectively. By moving the device at 1 m s–1, the concentration could be reduced to 50% in merely 15 seconds. In outdoor experiment, 23.5% decrease of haze concentration was measured.