A method of removing fixed pattern noise, comprising: S01: performing a single-frame segmented exposure on a pixel array; S02: reading a of the pixel array, comprising: S021: performing a soft reset, so as to set the reset signal of the pixel unit to an intermediate voltage, and reading a differential reset signal; S022: performing a hard reset so as to set the reset signal of the pixel unit to a high voltage; S023: turning on a transmission MOS transistor to enable an exposure signal of to photodiode to transmitted to the floating diffusion area, and reading a differential pixel transmission signal; S03: subtracting the differential reset signal from the differential pixel transmission signal to obtain an exposure signal with fixed pattern noise removed. Another method is removing fixed pattern noise and an image sensor are further provided.