A direct backlight module includes a reflective base, a buffer block, a lamp tube and a casing. Two opposite side regions of the reflective base both have two opposite openings located at two ends of each side region separately. The buffer block is disposed on the reflective base and positioned opposite to one of the openings. The lamp tube has two opposite electrodes at two ends of the lamp tube separately, and one of the electrodes is mounted in the buffer block. The casing covers the buffer block and there is an airflow channel formed by the combination of the inner chamber of the casing and the openings when the casing is installed in the reflective base.