The present invention provides a backlight simulating device comprising a light source simulating portion, an optical component simulating portion, a first distance measuring unit, and a second distance measuring unit. Multiple movable light-emitting members are equipped to the light source simulating portion. The optical component simulating portion is disposed adjacent to a light-emitting surface of each of the light-emitting members. The optical component simulating portion includes a light guide panel whose position can be changed relative to the light-emitting members. The first distance measuring unit acquires a distance between adjacent two of the light-emitting members. The second distance measuring unit acquires a distance between the light-emitting members and the light guide panel.