It is necessary to evaluate the mechanical reliability of the coiled fibers to evaluate the mechanical reliability of fiber coils applied in sensing fields, such as fiberoptic gyroscope and current sensors, besides the causes of fiber coatings and loop glues. A model is proposed for evaluating the mechanical reliability of the coiled fibers, which is based on the mechanical reliability model of the hauldistance telecommunication fibers by incorporating the bendinduced stress and the coiling tension. The model can simplify the inhomogeneous bending stresses distribution with the maximum stress value and the fact that the compressed stress in the inner side of the fiber natural axis is far small than the stretch stress outside. By these and the choosing of the parameters involved in the model, the conserved results are given using this simplified model. Several numerical caculations of mechanical reliability of various fiber coils with different fiber and bending radius are carried out using this model. The results show that besides fiber own inherent factors including the fiber radius and the fatigue factor, some process parameters, such as the circling tension, the ring radius and the screening tension also have a major impact on the mechanical reliability of coiled fibers.