The present disclosure provides an apparatus for removing bubbles in a flexible substrate. The flexible substrate includes a baseplate and a polyimide layer coated on the baseplate. The apparatus includes a chamber including a top wall, a sidewall, and a bottom wall, wherein the top wall, the sidewall, and the bottom wall define an accommodation space; a heating plate disposed in the accommodation space; and a cooling conduit embedded in at least one of the top wall and the sidewall of the chamber.