The invention provides a screen electricity-saving method, a screen electricity-saving device and a mobile terminal which are applicable to the technical field of mobile terminals. The screen electricity-saving method includes the steps of collecting images of the environment where the mobile terminal is located when a screen of the mobile terminal is located in the lighting state, obtaining the brightness value of each pixel point in the images, determining the environment brightness of the mobile terminal according to the brightness value of each pixel point, and adjusting the screen brightness of the mobile terminal according to the environment brightness of the mobile terminal. In the embodiment of the screen electricity-saving method, the screen electricity-saving device and the mobile terminal, the situation that a user cannot clearly see the content displayed on the screen when the environmental light is bright or dark is avoided, the problems that operation of the screen brightness adjusting mode of the mobile terminal is complex, the user time is wasted, the electricity-saving efficiency is reduced, unnecessary electricity consumption is caused, and the service life of the screen is shortened are solved, the user time is saved, the electricity-saving efficiency is improved, the electricity-saving electricity consumption is reduced, and the service life of the screen is prolonged.