With the improvement of composite material properties and their application level， composite single-lap bolted structures are increasingly widely used in aircraft structures. Practice has shown that a key factor affecting the fatigue life of single-lap structures is the magnitude of the tightening torque. To explore the effect of bolt tightening torque on the fatigue performance of single-lap structures， a fatigue damage model for composite single-lap bolted structures is established， and experiments are designed to verify the validity of the model. Through the analysis combining finite element method and experiments， it is found that when the tightening torque is 75% of the bolt failure torque， the bolted structure exhibits optimal stiffness characteristics， with less damage around the holes， the slowest increase rate of joint elongation in the stable stage， and the peak fatigue life as well as the best comprehensive performance. The above method can provide a reference for determining the torque of similar bolts.