A folded tunable single-mode TEA CO2 laser with two beams has been described. This laser can produce two beams which have the temporal coincidence of the pulses. Each beam can be tuned by grating independently within the range of 9.2μm~10.9μm. The highest peak powers of the single-mode/single-line output and the multi-mode/single-line output are about 1MW and 4 MW respectivety. In this paper Authors discuss the optimum transmittance and the mode selection of this laser and the temporal coincidence of the pulses. Some experimental results are given.