Terahertz (THz) radiation can penetrate many materials that are opaque to visible light, such as non-metal and non-polar materials, and these materials′ X-ray imaging are relative lower. Thus, THz imaging for security and quality control application has been paid great attention. Actual measurement on the THz characteristics is an important part of THz imaging technology. In this paper, THz laser pumped by a CO2 laser was used to measure polytetrafluoroethylene absorption characteristics and transmission beam profile. The absorption coefficients of polytetrafluoroethylene were achieved experimentally at wavelength of 70.51 μm, 96.5 μm, 118.83 μm, 122.4 μm, 158.51 μm, 184.31 μm and 214.58 μm.