The extinction characteristic of graphite smoke at 337 μm was calculated on the basis of Mie scattering model. And the extinction characteristics of it at conventional infrared bands(3-5 μm, 8-12 μm) and representative wavelength of laser(1.06 μm) were calculated later. The results indicate that the mass extinction coefficient(MEC) of the smoke at 337 μm is smaller by 1-2 orders of magnitude than that of other wavelengths or wavebands. Then, the transmission experiments about two kinds of smoke with different diameters of graphite particles were conducted respectively at those wavelengths and wavebands mentioned above. Finally, the MECs at 337 μm, 1.06 μm, 3-5 μm and 8-12 μm were deduced, and corresponding experimental results were contrasted. The MECs of two kinds of smoke at 337 μm are all less than 0.045 m²/g, and the values at other wavelengths or wavebands are further higher than it. The final results demonstrate that THz wave of 337 μm has stronger penetration capacity for smoke.