For the sake of environment protection, shallow formation waters were studied for the preparation of guar gum fracturing fluids in gas fields, west Sichuan. The fracturing fluid prepared with formation water had viscosity of 100 mPa·s after shearing 60 min(170 s-1) at 45 ℃, rate of permeability impairment of only 23.86%, surface tension of 27.82 mN/m, rate of swelling reduction of 87.5%, residue content of 518 mg/L. The formation water fracturing fluids were successfully used in SF382 and SF384, which respectively improved natural gas production of 1.14×104 m3/d and 1.68 ×104 m3/d. This technology enabled the reuse of formation sewage water in gas fields.