The construction, glow discharge stability and operation characteristics of high pressure long life-time sealed-off kW level transverse-flow COg lasers are reported. The effects of putting silica gel into the vacuum chamber, cooling the cavity region effectively and increasing pressure on the long-term sealed-off operation have been discussed.With gas flow velocity of 45m/s, gas mixture pressure of 82mmHg, active region length of 80cm, an output power of 1350W is obtained, with an electro-optic efficiency of 15.6% and CW operation time of over 30 hours.