Aiming at the influence of reflective electrowetting display on the definition and contrast of the content on the display under different ambient light, this paper proposes a brightness correction method based on preserving the difference of visual response of adjacent grayscale under different ambient light. The difference is consistent with the response difference under reference ambient light. At the same time, in order to achieve precise modulation of the electrowetting display, the corrected brightness is subjected to secondary nonlinear correction. The method makes the relationship between the corrected voltage and the brightness curve more linear, improves the contrast of the electrowetting display, increases the image detail, and optimizes the display effect.