Wide dynamic range is an important index of the resonator fiber optic gyro (RFOG). The dynamic range is related to the parameters of the fiber ring resonator (FRR). After adopting the appropriate parameters, the resonant curve of a FRR and the synchronous demodulated curve are measured. Based on the closed-loop frequency locking technique, the wide dynamic range is obtained, while the linearity is guaranteed. The experiment’s results show that the dynamic range is ±480 deg/s with less than 1% nonlinearity, and that the bias stability is 0.04 deg/s over 2000 s. This Letter demonstrates the scheme for a RFOG with a wide dynamic range.