The thermal aging effect of glass fiber reinforced composites (GFRP) under the influence of different time needs to be studied urgently. In this paper, the complementary nondestructive testing technology which combines Acoustic Emission(AE) and Digital Image Correlation(DIC) technologies was used to monitor the damage process of three-point bending specimens after thermal aging at 0, 4, 8 and 16 days respectively. Finally, the effect of prefabrication defects on the fiber-matrix interface properties of composites after thermal aging was analyzed. K-means cluster analysis was performed on the AE signals and global strain field measurements were performed by DIC to characterize the effects of prefabrication defects and thermal aging time on the mechanical behavior and deformation damage process of GFRP. Acoustic emission signals can classify various types of damage, and through the analysis of debonding signals, it was found that when crosslinking inside the laminate, the debonding signal was reduced and distributed after the failure load; as the thermal aging progresses to the stage of moisture volatilization, the debonding signal increased and was evenly distributed in the pre-fracture and post-fracture stages. For prefabricated fiber fractured laminates, the crosslinking phenomenon will reduce the number and amplitude of fiber fracture signals during laminate loading, and the maximum strain value will be reduced, which will effectively improve the carrying capacity of the laminate. The combination of acoustic emission clustering analysis and digital image correlation technology can better describe the damage evolution of fiber-reinforced composites under different thermal aging conditions, which is helpful to further reveal the influence of defects and thermal aging time on internal damage mechanism.