Two schemes of fiber Bragg grating(FBG) strain rosettes:right and triangle rosettes,which are made of three fiber gratings along single optic fiber respectively,were presented and demonstrated.They are bonded to constant strength beam to measure values and directions of main strains and to study the performance of plane strain measurement of FBG rosettes.The results show that there are good agreements between the measured directions of main strains and the theory,so does the results of two types of FBG rosettes.