Abstract: The Daniudi gas field had the characteristics of low pressure, tight, poor physical property, water locking damage and sensibility etc., and only reformation measures of reservoir could obtain high productivity. On the basis of conventional 0.45% guar gum fracturing fluid system, a guar gum fracturing fluid system with ultra-low concentration was developed through the adjustment and optimization of the cross-linking agent, cleanup additive and gel breaker. The result showed that the concentration of hydroxypropyl guar gum could decrease from 0.45% to 0.30% by using the ultra-strong crosslinker SITAR-11, the viscosity of crosslinked jelly was more than 140 mPa·s under 90 ℃, 170 s^-1 after shearing 120 min, and it still had fine prop-carrying ability under 38% high sand concentration. By using biochemical mixed efficient cleanup additive ZITHE-34, the surface tension of the gel breaking fluid reduced to 22.4 mN/m, and the interfacial tension reduced to 0.9 mN/m respectively. By using fracturing gel breaking enzymes FANFA-06 and APS coupling gel breaking technology, the residue value reduced from 300 mg/L (after gel breaking by conventional system) to 180 mg/L, which greatly reduced the formation damage. The fracturing operation was conducted to two horizontal wells in reservoirs of Shan 1 and He 1 in Daniudi gas field respectively, sand proportion and construction pressure all met the design requirements in the process of fracture, the flowback rates after fracturing were 28.2% and 30.1%, the open-flow capacities were 7.7×10⁴ m³/d and 10.8×10⁴ m³/d, and the yield-increasing effect was remarkable.