The invention provides a method and a system for displaying an UI (user interface) by an LED (light emitting diode) lamp. The method comprises the following steps of obtaining the UI, designing an image with UI display content, and transforming the image through a color space, so as to obtain a gray image array; dividing the gray image array by a gray connected domain dividing algorithm, so as to obtain a plurality of connected domains; analyzing the multiple connected domains by an image analysis algorithm, so as to obtain characteristic quantity; according to the characteristics quantity, controlling the display of an LED lamp array, so as to improve the interaction experience of users.