Using a Ti:Sapphire rod grown in China a Single-transverse-mode CW laser has been demonstrated with an astimagition compensated fold cavity of four mirrors.The pumping source was an argon laser with all lines output. With three sets of cavity mirrors the tuning ranges were 680～760 um,730～ 840 um, and 970～1010 um respectively,while the peak power wavelength was 780 um.Up to 2.35W of output power and 33. 49% of slope efficiency were obtained with an output transmissivity of 11.76% at 780 um for a pump power of 10.0 W.