This paper demonstrated the importance of bolt tightening in engineering application, and given the injector clamp tightening of engine model. We given the calculation method of snug torque and angle of torque-angle tightening of bolt, and this calculation method of bolt tightening has an important control function. In addition, the torque and angle Adjustment method was given. We introduced the Experimental Study. Finally, the injector clamp tightening bolt M8×1 of JX4D30X engine as an example, Examples proved that the results of theoretical calculation and experimental study uniform. These studies have not been involved in other papers.