A fiber optic gyro (FOG) uses Sagnac effect in fiber coil to detect rotation component about a sensing axis that is perpendicular to the plane of the fiber coil. The fiber coil is the key component of FOG, and its winding quality affects the integrated performance of FOG directly, so it is necessary to roundly test the fiber coil winding quality. In view of the limitation of present testing methods of FOG fiber coil, a transient characteristic testing method of FOG fiber coil based on temperature excitation was proposed, which could completely represent the winding quality of fiber coil. A computational three-dimensional fiber coil model was established. With finite element analysis technique, numerical simulations were carried out to quantitatively analyze the influence of fiber coil unsymmetry and sectional temperature excitation position accuracy on the transient response of fiber coil. At the meantime, the corresponding temperature excitation experiments were made. The experimental results are in good agreement with numerical simulation results. Finally, the transient characteristic testing method is identified feasible and acceptable by theory and experiment.