Abstract: The Y443-111 packer was mainly used in the high-temperature and high-pressure (HTHP) gas wells in the Kuqa Piedmont structure , and it was prone to build the pressure during fluid displacement. In serious cases, the packer was set ahead of time, resulting in the test drilling fluids failed to be completely replaced by annulus protection fluid, which could cause the corrosion of tubing and casing. In view of the above problems, the causes of the failure of Y443-111 packer during fluid replacement were analyzed. It was found that the main factor was the small size of gap between the packer and the casing, and the secondary factors were the high displacement rate of fluid and the poor cleanliness of the wellbore. For these reasons, measures such as reducing fluid displacement rate and the outer diameter of the packer, cleaning up the wellbore impurities, optimizing the properties of oil based drilling fluids, and improving the quality of wellbore operation fluids were taken. These measures had been applied in the field for 43 wells with a success rate of 97.6%, which effectively controlled the packer failure of HTHP gas wells in the Kuqa Piedmont structure and ensured the safe downhole operations and smooth well completions.