A microwave drying device has a processing box. Two mounting openings are formed on an external mounting wall of the processing box. Two suction partitions are mounted in the processing box and divide an inner space of the processing box into a microwave drying space and two suction spaces. The microwave drying space is located between and connects to the two suction spaces. Multiple channel partitions are mounted in the microwave drying space to form a meandering wave travelling channel. Two opposite ends of the wave travelling channel connect to the two mounting openings respectively. Two microwave emitting modules are mounted on the external mounting wall and emit microwaves toward the two mounting openings respectively. Multiple openings are formed in the processing box such that a film can travel through the processing box. Therefore, drying speed is greatly increased, and the drying device is more compact.