The present disclosure provides a dimming method for an LCD device. The LCD device includes a dimming screen and a display screen. The dimming screen is divided into N×M dimming areas, and the display screen is also divided into N×M display areas. N and M are respectively positive integers greater than or equal to 1. The dimming areas correspond to the display areas in a one-to-one relationship. The dimming method includes determining a regional eigenvalue of each of the dimming areas according to image data, determining a dimming brightness of each of the dimming areas according to each regional eigenvalue, and dimming each of the dimming areas according to each dimming brightness. The present disclosure also provides a dimming screen for use in the dimming method and an LCD device using the dimming method.