A backlight module includes a lamp tube, a light guide plate and a light guide unit. The light guide plate has a light incident side. The light guide unit is in contact with the light incident side of the light guide plate. The light guide unit and the light incident side cooperatively form a receiving tunnel. The lamp tube is disposed in the receiving tunnel. The light guide unit is detachable from the light guide plate. Another backlight module is also provided. The present backlight module can be assembled conveniently and quickly, and has a relatively high light energy utilization rate.