Dry filtration system, adsorption method and medium efficiency filtration are adopted. Dry spray booth is composed of chamber body, air exhaust device and paint mist treatment device. The chamber body is generally galvanized. The exhaust device is composed of exhaust fan and air duct. The air volume of exhaust fan directly affects the direction and speed of air flow in paint mist room. The treated clean air is discharged into the environment by exhaust device. Paint mist treatment device is installed in front of the exhaust device to remove paint mist in the air. Paint mist treatment device collects paint mist by slowing down the flow rate and increasing the contact opportunity between paint mist particles and filter materials; in the process of use, when the ventilation is too large or the air exhaust effect is affected by the filter being blocked by paint mist gradually, the air discharge can be adjusted by regulating valve. If the adjustment is ineffective, the filter should be replaced.