A pixel circuit, a handwriting display panel and a handwriting display system are provided. The pixel circuit includes: a write-in control circuit, a light-emitting circuit, a display control circuit and an erasing control circuit. The write-in control circuit includes a photosensitive switch, and the photosensitive switch is capable of being turned on under illumination of first light; the light-emitting circuit includes a first light-emitting component, which is configured to emit the first light to illuminate the photosensitive switch where the photosensitive switch is turned on; the display control circuit includes a display unit, which is configured to perform display operation where the photosensitive switch is turned on; and the erasing control circuit includes an induction switch, and the induction switch is controllable to be turned on.