An apparatus for laminating substrates includes a laminating fixture having an open-topped recessed space formed by a pair of corresponding sidewalls for holding a target substrate therein. The recessed space is communicable with an air evacuation passage. A supporting structure is formed in the recessed space for supporting two opposite ends of a flexible substrate thereon, such that a bottom of the flexible substrate is spaced from a laminating surface of the target substrate by a predetermined distance. A soft plate is disposed over the open-topped laminating fixture to form an airtight chamber in the laminating fixture. When the airtight chamber is vacuumed using a vacuum pump via the evacuation passage, the soft plate is subjected to a suction pressure and downward deformed to press the flexible substrate downward, causing the flexible substrate to deflect to attach its bottom on the laminating surface of the target substrate.