Well GL-1 was completed at the depth of 6300.83m. With the expected bottom temperature up to 260℃, the drilling fluid with 260℃ high temperature tolerance was used in the 6 months construction. The application shows that this drilling fluid has advantages of good temperature tolerance (260℃), strong anti-pollution ability, good lubricity with light damages to oil and gas reservoirs, is conducive to hole wall stability. The successful construction of this well provides safe and effective technical guarantee for the further exploration and development with high temperature in deep layer of Daqing oilfield.