Lightcured composite resin is an important material in densitry for beauty and restoration. Fiber Bragg gratings(FBG) is used to determine composite resin shrinkage during the lightcuring. Because FBGs are both sensitivity to temperature and strain, two different kinds of FBGs were used to calculate the temperature and strain respectively. One of the FBG was bare, and the other was chemical plated FBG, both of which were embedded in one sample of resin simultaneously. LED light source was used for light curing. Real time changes of temperature and shrinkage strain were gained. The experiments showed that the resin expressed strong shrinkage strain and temperature variation because of the polymerization reaction during the curing. The results are helpful for understanding the shrinkage and temperature change of the materials and improving more prefecable treatment effect.