There are provided a backlight scanning method and a device thereof. The method comprises: dividing an edge lighting type backlight source into an upper side optical region and a lower side optical region; turning on the light sources at the upper and lower sides respectively after the response of the liquid crystal corresponding to the pixels in the last row of the upper and lower side optical regions is stationary; turning off the light sources at the upper and lower sides respectively when the next response period of the liquid crystal corresponding to the pixels in the first row of the upper and lower side optical regions starts. The method solves the difficulties of applying the scanning backlight to the edge lighting type backlight source by respectively controlling the timings of turning on and off the light sources at the upper and lower sides, whereby the application scope of the scanning backlight is broadened.