During the hydraulic fracturing process for shale gas wells, the fracturing fluid is injected into the wellbore with large pump rate. The bottom-hole temperature will decrease sharply, which increasing the risk of casing failure. Based on the actual data of shale gas wells, the influence of rheological parameters of fracturing fluid on heat transfer coefficient is analyzed. A transient thermo-pressure coupling model of casingcement sheath-formation combination is established. Sensitivity analysis is conducted for different pump rates, pressures and injection temperatures. The results indicate that: i. The rheological parameters of fracturing fluid can affect the heat transfer coefficient between the fluid and borehole wall, which in turn affects the temperature distribution at the bottom of the wellbore. ii. The increasing of pump rate will drastically reduce the bottom-hole temperature, then thermal stress generating on the casing. iii. The higher the original reservoir temperature, the greater the influence of the temperature. iv. The casing stress decreases then increases with the increasing of fracturing pressure. Therefore, the rheological parameters of fracturing fluid should be chosen reasonably to reduce the heat transfer coefficient. What is more, it is crucial to choose the appropriate fracturing pump rate, fracturing pressure and injection temperature, as far as possible to reduce the bottom-hole temperature difference, which avoiding excessive casing stress to enhance the casing safety for fracturing shale gas wells.