The present invention discloses a unit for validating an in situ decontamination effect, including a connecting end. A left end of the connecting end is in communication with any space that needs gas decontamination. A right end of the connecting end is connected to a closed isolation damper. A right end of the closed isolation damper is connected to a hollow decontamination validation chamber. A sealing cover is sleeved over an outer wall of the decontamination validation chamber. A mesh cup is placed inside the decontamination validation chamber, and the mesh cup is used for placing a bioindicator. In addition, the present invention further discloses a device for filtering biologically contaminated air, including a unit for validating an in situ decontamination effect and a hollow box installed with a high efficiency particulate air (HEPA) filter. The unit for validating an in situ decontamination effect is in communication with the hollow box. In the present invention, an actual decontamination effect of the HEPA filter after gas decontamination can be validated reliably in time, thereby effectively preventing pathogenic microorganisms that exist on the surface of the HEPA filter from spreading to the external environment, avoiding polluting the external environment, and ensuring personal safety.