Abstract: The changes of bending loss in 1 310 nm wavelength and 1 550 nm wavelength with different bending radius of optical fiber is measured,and the effect of different working wavelength light and bending radius in optical fiber on bending loss is compared.The result shows that the bending loss coefficient decreases with the increase of bending radius,withthe oscillation phenomenon appearing；in large bending radius,bending loss changes gently,but the bending loss is more likely to occurin 1 550 nm wavelength than in 1 310 nm wavelength.The bending loss show sharp oscillation with small bending radius.At this time,the sensitivity of two optical wavelengths to the bending loss become large alternately.

Key words: optical fiber, working wavelength, bending radius, bending loss