In order to promote the hydration process of traditional hydroxypropyl guar gum (HPG), a liquid guar gum thickening agent (LGC) was fabricated, which mainly consists of white oil, surfactant and emulgator, with simpler preparation, better dispersion ability and faster swelling. The viscosity of tap water and sea water with 1.0% LGC and 0.15% methanal was 110.11 and 112.40 mPa·s separately under low-speed mixing for half an hour at room temperature, which was the same as standard base solution with the same effective amount of HPG. Base fluid prepared with LGC was not sensitive to pH value and salinity of any water source. Both of sea water and fresh water could be used, which could dramatically reduce the construction cost in off shore oil production. Base fluid of LGC or HPG (0.4% effective content HPG) with organic borate-zirconate cross-linker CYS-1 could be completely broken with final viscosity 3.542 and 2.243 mPa·s and glue residue 476 and 432 mg/L by using 0.08% ammonium persulfate (APS) at 95 oC for 4 hrs. The base fluid with 1.0% LGC (40% effective content) and CYS-1 had initial filtration Vsp of 1.907′10-4 m³/m², filtration coefficient Cw of 0.997′10^-4 m/min^? and average filtration Vcm of 0.366′10-4 m³/(m²·min) at 120oC. For powder HPG, the swelling time of base fluid with 0.6% HPG, CYS-1 and other additives was up to 24 hrs, and the viscosity was 180 mPa·s under the shear rate of 170 s^-1 at 160oC. However, for the LGC sample, under the same experiment condition as above, the swelling time was only less than 30 min, and the viscosity of base fluid could be 190 mPa·s which kept above 122 mPa·s even under high shear rate of 1000 s^-1 for 3 min at 170oC. LGC met the high requirement of rapid preparation, fast swelling and high temperature resistance under high shear rate.