The power quality affects the normal operation of electrical equipment and power system directly. Accurate measurement of voltage amplitude and frequency is a prerequisite for the analysis of power quality. In this paper, a fiber Bragg grating(FBG) voltage sensor based on CCD demodulation is proposed. Using the inverse piezoelectric effect of piezoelectric ceramics to change the wavelength of the FBG attached to the piezoelectric ceramic, the purpose of detecting the voltage is achieved. The relationship between the voltage and the wavelength of grating is analyzed theoretically. The experiments show that the nonlinear error is 2.998% and loaded voltage sensitivity of the sensor is 8.47 pm/V, which can detect the waveform of the voltage below 50 Hz. This method provides a reference for assessing the power quality in complex environments.