Addressing issues such as inconsistent preload and short-term relaxation in bolted connections，this study focused on composite bolted connection structures.Based on the formation mechanism of preload in conventional bolts，the principles of preload generation in high-lock bolts was analyzed，deriving the torque-preload relationship for high-lock bolts.Through bolt tightening tests，the study determined key parameters such as locking torque，breakaway torque，and fitted the torque-preload relationship curve for high-lock bolts.Single-factor experiments were designed to analyze the effects of tightening speed，lubrication conditions，and tightening steps on the consistency of bolt connection preload.The tests show that tightening speed and lubrication conditions have a significant impact on the consistency of bolt preload force.Higher tightening speeds and the application of lubrication can achieve greater preload force， but the consistency of preload force deteriorates.To address the issue of short-term preload decay after bolt tightening，a 48 h natural relaxation test was designed to investigate the natural relaxation patterns of bolt preload in composite laminated structures under various conditions such as tightening speed， lubrication conditions，and tightening steps.The results indicat that lubrication conditions have the most significant impact on the natural relaxation of bolt preload in composite laminated structures.