A novel micro-deflection testing system based on fiber Bragg grating（FBG）sensing technology is demmonstrated.A FBG is adhered on the free end of the standard cantilever beam with special gelatin.When the loads are applied to the end of the cantilever beam

the FBG will cause deformation along the fiber longitudinal direction.According to monitoring the wavelength shift of the FBG

the variation of the micro-flexivity of cantilever beam can be obtained.The experiment results demonstrate that the testing range of this system can reach 0～51 μm

the sensitivity of this system is about 0.05 μm

and the related linear regression coefficient is 0.999 7

The nonlinearity error is less than 0.1 %.