Aiming at the issues of limited acoustic path and insufficient accuracy in acoustic time-difference extraction in ultrasonic measurement of axial stress for high-strength short bolts, this paper proposes a bolt axial stress measurement method based on ultrasonic coda wave interferometry. An axial stress measurement model for bolts based on coda wave acoustic time difference is established, which enhances the stress sensitivity of the time difference by extending the equivalent acoustic path length. To effectively suppress measurement errors induced by coda wave interferometry, an adaptive threshold extraction algorithm was proposed based on a linear interpolation error model. With the objective of minimizing the maximum error and thereby substantially improving the accuracy of acoustic time difference estimation. The formation and propagation of internal coda waves in bolts are investigated via finite element simulations, and the results agree well with the theoretical analysis, thereby supporting the coda wave interferometry-based measurement model. An ultrasonic experimental platform for bolt axial stress measurement was constructed, and comparative calibration tests were performed on multiple sets of bolts with different materials and specifications using both the proposed method and the conventional ultrasonic measurement method. The results show that the proposed coda wave adaptive threshold method exhibits better linear fitting accuracy in the entire stress range, with step-like distortion in the low stress regime essentially eliminated and measurement stability significantly improved. When applied to high-strength short bolts, the proposed method achieves an average measurement error within 5%, representing a clear improvement compared with traditional methods (with an average error of approximately 8% to 10%). This method enables high-accuracy measurement of bolt axial stress using only a single contact longitudinal wave transducer, avoiding additional sensor configurations and complex experimental conditions, and thus offering strong engineering applicability.