The invention discloses a light modulation system. A light modulation circuit comprises a processing module, a memorizing module and a driving module. The memorizing module stores light emitting state data of a lamp. The processing module reads the light emitting state data in the memorizing module after being electrified, and outputs a corresponding lamp driving signal to the driving module. The driving module drives the lamp to work in a corresponding light emitting state according to the lamp driving signal. The technical scheme of the invention also provides a light modulation circuit with a memorizing function.