This paper deals with the principle of bolt tightening methods, such as torque, rotation angle and hydraulic stretch.Some preload control means and their precision were discussed.

• 本文介绍了实际生产中常用的扭矩法、螺母转角法和液压拉伸法的基本原理,并给出了各种预紧力的控制方法及其所能达到的精度,对安装和维修有一定的指导意义。