Aiming at both strain and temperature sensitivity problem of fiber Bragg grating (FBG) strain sensor,this paper presents an FBG strain sensor based on circular ring with stress deformation principle of structure,and the theoretical analysis and sensor performance test are conducted.The circular ring is the sens itive structure of the strain sensor. We can achieve the surface strain of the monitored target by pasting the FBG at the ring vertical and transverse diameters.A series of optical fiber sensing experimental results show that the sensitivity of our prepared sensor is 3.76pm/με with linearity of 0.9999,and the affection of temperature is almost eliminated.It can be applied to strain monitoring with hig h precision demand and high temperature effect,especially for metallurgy casting crane.