The work aims to improve the reliability of bolted joints by analyzing the self-loosening mechanisms of bolted joints subject to dynamic shear load and investigating the effect of lubricating grease on the self-loosening behaviour of bolted joints. Based on the self-designed experimental equipment, loosening tests were carried out to the bolted joints under the shear load to analyze the effect of two lubricating greases (molybdenum disulfide grease and lithium grease) on the self-loosening behavior of bolted joints. After tests, the damage of the first engaged thread was analyzed by scanning electron microscopy (SEM). The initial tightening torque of the bolted joints with lubricating grease was reduced by 30%~40% under the same preload. There was a critical value of shear load on bolted joints. When the amplitude of shear load was below a critical value, complete loosening would not occur. The critical value decreased when the first three engaged thread surfaces of bolts were lubricated (local lubrication), and then further decreased when all of the engaged thread surfaces of bolts were lubricated (complete lubrication). When the amplitude of shear load was smaller than the critical value, local lubrication was effective to improve the anti-loosening performance of bolted joints, and the loosening degree of the bolted joints was reduced by more than 20%. Microslip and fretting wear between the contact threads are the main loosening mechanisms of bolted joints. Adding lubricating grease at the thread interface can effectively reduce the fretting wear on the thread surface.