This study is aimed at investigating the measurement of contact stress and its distribution pattern across the attachment surface of an aero-engine casing flange. To begin with, a dynamic contact stress measurement system for casing flanges was established based on MXene flexible pressure sensors with an ultra-wide pressure monitoring range. The measurement system was sandwiched by two flanges, and up to 13 measurement points were distributed therein. The stress changes of the corresponding measurement points were obtained in real time according to the time-domain response of the sensor resistance change rate and the pressure calibration curve. The comparison of the test results with the simulation shows satisfactorily consistent trends, displaying stress errors lower than 7%. Subsequently, the influence of structural parameters and pre-tightening torque on contact stress were studied, and possible measures for improving the sealing performance were applied. The findings suggest that not only can the proposed analytical method and measurement system provide accurate dynamic measurements for contact stresses, but the studied influencing relationship can also serve as a reliable reference for upcoming sealing performance optimization design for flanges. Last but not least, owing to the universal applicability of the methods presented, this research method also offers an invaluable guidance for contact stress measurements and distribution analyses of various casing flanges.