The glass fiber/epoxy composite laminate($[0/90_4]_s$) in which optical fiber sensors are embedded, are fabricated to investigate fatigue characteristics of smart composite structure. Resin rich area formed around the embedded optical fibre can cause substantial effect on fatigue life of smart structure. In this study, a length ratio parameter, i.e. the ratio between resin rich area and specimen width, was used to express fatigue test results quantitatively. Embedding of optical fiber sensors has significant effect on fatigue life of specimens. About 30 % and 80 % fatigue life reduction was caused at a length ratio parameter 0.0875 and 0.6125 respectively compared to the fatigue life of specimens without the optical fiber sensors. However the effect of resin rich area on matrix crack density is not so significant. Initiation point of matrix crack is edge of specimen if length ratio parameter is lower than 0.0875, while crack initiation point becomes inside of specimen as the length ratio parameter is larger than 0.6. Embedded optical fiber tends to prevent matrix crack from propagation.
