The invention discloses a city-level air purification unit. Polluted air in a city is output from an air inlet part for air suction to a purification part in a suburban area, air purified by the purification part is output into the city, filter replacement of air in the city is formed, and a large-range air purification cycle of the city is formed; main consumed energy for air purification includewater and electric power, water is based on a cyclic cleaning principle of a cleaning room, a sedimentation tank and an impounding reservoir, and the city-level air purification unit has the characteristics of low use cost and high practicability; compared with exiting cleaning means such as mist-spray car cleaning and the like, although the initial-stage construction investment is higher, late maintenance and operating cost of the unit is far lower than that of the existing technological means of mist-spray car cleaning, purification capacity can be greatly improved, and the unit has high social value and suitable for being popularized and applied.