Abstract: The pre-tightening force of bolt plays an important role in maintaining the stability of surrounding rock in coal roadway. However, the instability of roadway caused by the loss of pre-tightening force in field engineering generally occurs. In this paper, the transformation relationship between bolt pre-tightening torque and pre-tightening force is analyzed. The phenomenon of bolt pre-tightening force loss in Wujiagou Coal Mine is studied. The characteristics and causes of bolt pre-tightening force loss behavior are revealed, and the influence of bolt on surrounding rock stress and displacement distribution under different pre-tightening force loss rates is explored. The results show that there is a linear positive correlation between the pre-tightening torque and the pre-tightening force. However, due to the friction between the supporting components and the surrounding rock conditions of the roadway, the average loss rate of the pre-tightening force of the bolt ranges from 20 % to 58 %. The increase of the loss of the pre-tightening force of the bolt can lead to the decrease of the stress of the shallow surrounding rock of the roadway, the increase of the deformation of the surrounding rock and the depth and volume of the plastic zone, and the decrease of the bearing capacity of the surrounding rock. This study can provide guidance for on-site bolt pre-tightening construction and improve the stability of roadway surrounding rock at the initial stage of support.