A light-modulating element, a backlight module, a display device and a method for controlling the same are provided. The light-modulating element includes a first substrate and a second substrate arranged opposite to each other, and a polymer dispersed liquid crystal layer located between the first substrate and the second substrate. The light-modulating element is divided into a plurality of light-modulating zones, and the light-modulating element further includes a first electrode and a second electrode located in each of the plurality of light-modulating zone. A plurality of first electrodes located in different light-modulating zones are independently arranged, and the first electrode and the second electrode are configured to drive a deflection of polymer dispersed liquid crystal molecules in polymer dispersed liquid crystal layer.