A backlight module includes an optical assembly, a plurality of first light units, and a light guide plate. The optical assembly includes a base film, a first conductive layer, and a first reflective layer. The first conductive layer is disposed on the base film, and the first reflective layer is disposed on the first conductive layer. The first reflective layer includes a first part and a second part. The first part is connected to the second part. The plurality of first light units are disposed on the first part and extend through the first part to be electrically connected to the first conductive layer. The light guide plate is disposed on the second part.