A backlight controlling method, comprising: for each display block in a screen, acquiring (202, 301) gray scale values of respective pixels in an image needing to be displayed in the display block, the screen including at least one display block; characterized in that it comprises: acquiring (204, 302) the minimum value from a predetermined number of maximum gray scale values according to the gray scale values of respective pixels; if the minimum value reaches a gray scale value threshold, controlling the gray scale values of respective pixels to be constant, and controlling a backlight lightness of the display block to keep a maximum backlight lightness (206, 303); and if the minimum value does not reach the gray scale value threshold, acquiring a gray scale value subinterval within which the minimum value is located; acquiring a duty ratio corresponding to the gray scale value subinterval according to a predefined corresponding relationship, wherein the predefined corresponding relationship includes a corresponding relationship between different gray scale value subintervals and different duty ratios, a magnitude of the duty ratio increases with a magnitude of the gray scale value, a magnitude of the duty ratio increases with the backlight lightness, and the duty ratio corresponding to the gray scale value subinterval [P 0, P max] having the maximum gray scale values is 100%, wherein P 0 is the gray scale value threshold, P max is a maximum gray scale value which can be displayed by the screen, and 0<P 0 ≤P max; and sending a pulse width modulation PWM signal with the duty ratio to a backlight driving IC, the PWM signal being for instructing the backlight driving IC to control the backlight lightness of the display block according to the duty ratio. for each display block in a screen, acquiring (202, 301) gray scale values of respective pixels in an image needing to be displayed in the display block, the screen including at least one display block; characterized in that it comprises: acquiring (204, 302) the minimum value from a predetermined number of maximum gray scale values according to the gray scale values of respective pixels; if the minimum value reaches a gray scale value threshold, controlling the gray scale values of respective pixels to be constant, and controlling a backlight lightness of the display block to keep a maximum backlight lightness (206, 303); and if the minimum value does not reach the gray scale value threshold, acquiring a gray scale value subinterval within which the minimum value is located; acquiring a duty ratio corresponding to the gray scale value subinterval according to a predefined corresponding relationship, wherein the predefined corresponding relationship includes a corresponding relationship between different gray scale value subintervals and different duty ratios, a magnitude of the duty ratio increases with a magnitude of the gray scale value, a magnitude of the duty ratio increases with the backlight lightness, and the duty ratio corresponding to the gray scale value subinterval [P 0, P max] having the maximum gray scale values is 100%, wherein P 0 is the gray scale value threshold, P max is a maximum gray scale value which can be displayed by the screen, and 0<P 0 ≤P max; and sending a pulse width modulation PWM signal with the duty ratio to a backlight driving IC, the PWM signal being for instructing the backlight driving IC to control the backlight lightness of the display block according to the duty ratio. acquiring (204, 302) the minimum value from a predetermined number of maximum gray scale values according to the gray scale values of respective pixels; if the minimum value reaches a gray scale value threshold, controlling the gray scale values of respective pixels to be constant, and controlling a backlight lightness of the display block to keep a maximum backlight lightness (206, 303); and if the minimum value does not reach the gray scale value threshold, acquiring a gray scale value subinterval within which the minimum value is located; acquiring a duty ratio corresponding to the gray scale value subinterval according to a predefined corresponding relationship, wherein the predefined corresponding relationship includes a corresponding relationship between different gray scale value subintervals and different duty ratios, a magnitude of the duty ratio increases with a magnitude of the gray scale value, a magnitude of the duty ratio increases with the backlight lightness, and the duty ratio corresponding to the gray scale value subinterval [P 0, P max] having the maximum gray scale values is 100%, wherein P 0 is the gray scale value threshold, P max is a maximum gray scale value which can be displayed by the screen, and 0<P 0 ≤P max; and sending a pulse width modulation PWM signal with the duty ratio to a backlight driving IC, the PWM signal being for instructing the backlight driving IC to control the backlight lightness of the display block according to the duty ratio.