China’s rapid expansion has tremendously increased the number of heavy haze days in the megacities and their vicinities. Indoor air quality and public health have also become significant research topics. This paper summarizes theories on cloud droplets capturing fine particulate matter, and describes the production of a non-filter air cleaning device based on ultrasonic atomization technology and negative ion technology. Then, several experiments were carried out in an 8m3 simulation cabin. Experimental results showed that the air cleaning device could decrease the PM2.5 concentration in the simulation cabin by 44.2% within 20 minutes, and down from 382.7μg/m-3 to 72.3μg/m-3 in about 50 minutes. This confirmed that the cleaning ability and efficiency of the air purification device was good, and the air purifying program was feasible. At the same time, there was no secondary pollution to the indoor air environment caused by a dirty filter that had not been replaced in time. Moreover, the air cleaning device has the function of regulating indoor humidity.