The present invention provides a PDP structure comprising a first substrate, a second substrate and a Waffle barrier rib structure located between the first and second substrate. The Waffle barrier rib structure comprises three first barrier ribs having different width and a plurality of second barrier ribs perpendicular to the first barrier ribs. The second barrier ribs are located between the two first barrier ribs, and connect the wider structure of the two first barrier ribs. Therefore, discharge spaces are formed. Because of different width, the height difference of the barrier rib structure is formed after thermal process. Hence, gas can pass through the barrier ribs structure between the front and the back substrate sealed together.