The content of insoluble substance in guar gum solution is high and its temperature resistance is poor. A novel anionic guar gum (GG) derivative was developed and grafted by modification with maleic anhydride. Compared with guar gum, the insoluble content of MAG solution decreased from 13 to 5%, the decomposition temperature of MAG increased from 285 to 308, and the viscoelasticity of MAG gel has been enhanced, especially elasticity. The rheological tests show that the corresponding fracturing fluid belongs to a non-Newtonian pseudoplastic one and the viscosity could maintain 50mPa.s for 2h under conditions of 150 degrees C and 170s(-1), which can be applied in a high-temperature well. It is noteworthy that the synthetic protocol of maleate esters guar gum (MAG) is easily available, low cost, and practical. It is conducive to the industrial application of MAG. The work showed a great significance to the modification of GG with acid anhydride for fracturing fluid.