The influence of air gaps on the response of transmission for a transverse-electric mode parallel-plate waveguide(TE-PPWG) with a single cavity and double cavities has been studied experimentally. As the air gap is larger than the resonant wavelength of high order cavity mode in the single deep grooved waveguide, only the fundamental cavity mode can be excited and single resonance can be observed in the transmission spectrum. Based on above observations, a tunable multiband terahertz(THz)notch filter has been proposed and the variation of air gap has turned out to be an effective method to select the band number. Experimental data and simulated results verify this band number tunability. This mechanical control mechanism for electromagnetic induced transparency(EIT) will open a door to design the tunable THz devices. The influence of air gaps on the response of transmission for a transverse-electric mode parallel-plate waveguide (TE-PPWG) with a single cavity and double cavities has been studied experimentally. As the air gap is larger than the resonant wavelength of high order Based on above observations, a tunable multiband terahertz (THz) notch filter has been proposed and the variation of air gap has turned out to be an effective method to select the band number. Experimental data and simulated results verify this band number tunability. This mechanical control mechanism for electromagnetic induced transparency (EIT) will open a door to design the tunable THz devices.