Provided are a light dimming method for alleviating inter-frame flicker and dimming device. The light dimming method includes that: an average luminance value Avgdata when a sender sends physical frames is calculated; whether inter-frame flicker is generated when the sender sends data or not is judged according to a ratio of Avgdata to an average luminance value Avglight in an illumination state; and if the inter-frame flicker is generated when the sender sends the data, the sender inserts a dimming frame in an idle pattern, wherein the dimming frame is used for compensating for a luminance difference between Avgdata and Avglight. A value of a duty cycle of the physical frame sent to regulate the luminance of the light source in the idle pattern of the sender is within a certain range, and is not required to be accurately equal to a duty cycle of a line coding method adopted for a physical layer.