Abstract: The FBG sensors, embedded in the triangle area of the T-stiffened panels, were employed to online-monitor the strain of the composite T-stiffened panels during its impact testing and compression testing. The effect of impact location and impact energy on the strain measured by the FBG sensors was studied. The accuracy of the FBG sensor during the impact and the compression was analyzed. The experimental results showed that the max-strain of impact measured by the FBG sensors decreased with the increase of the distance between the location of impact and the FBG sensors (impact distance) under the same impact energy. The FBG sensors did not fail while visible damages are induced in composite T-stiffened panels, and the spectrum of the FBG sensor maintained single peak, the accuracy of the FBG sensor was assured. The procession of the impact and the compression monitored by FBG sensors on-line were initially realized.