In this paper, the structure and the experimental results of a mirrorless FIR laser is described. A tunable TEA CO2 laser is used as its pumping source. Its output energy is about 1J at both 9R(22) and 9P(20) lines. Output energy of 0.5 mJ at =496m is obtained with CH3F molecular pumped by CO2 laser 9P(20) line; 1mJ =385m is obtained with D2O pumped by 9R(22) line. A thermopile and a Fanry-Perot interferometer are used to measure output energy and wavelength of FIR laser radiation respectively.