In order to meet the strain measurement needs of different occasions, a sensitivity coefficient adjustable fiber Bragg grating (FBG) strain sensor based on circular ring structure is proposed. By adjusting the geometric parameters of the annulus on an elastic substrate, flexible regulation of sensitivity is achieved. At the same time, temperature-compensated FBG is utilized to eliminate the interference of environmental temperature changes on the measurement results. A theoretical model of the sensor has been established, and a desensitized FBG strain sensor is developed. The measurement performance of this sensor is verified through finite element simulation and experiments. The experimental results show that the sensitivity of the sensor within the range of ± 3 000 με is 0.49 pm/με, and the linear correlation coefficient is above 0.99. Meanwhile, its repeatability error is 0.68% and hysteresis error is 2.96%, demonstrating good stability and reliability.