A flexible display and a controlling method thereof are provided. The flexible display includes a plurality of pressure sensors, a display unit and a processing unit, wherein the processing unit is connected to the pressure sensors and the display unit. The processing unit obtains pressure values from each of the pressure sensors within a time unit and generates a pressure area and a pressure variance according to the pressure values from each of the pressure sensors. The processing unit further determines a display mode of the display unit according to the pressure area and the pressure variance. Therefore, the flexible display is capable of providing several kinds of display mode only based on the equipped pressure sensors.