The present invention provides a method for manufacturing a PDLC display device and a PDLC display device. The method for manufacturing a PDLC display device according to the present invention includes mixing PDLC with graphene nanoparticles to improve the response speed of the PDLC and reduce a driving voltage of the PDLC, and also combines QDs to make a novel high color saturation display device, which requires no alignment layer and polarizer, providing a simple manufacturing process, showing an innovated and unique displaying effect, demonstrating at least four displaying modes of red, green, blue, and indistinctness, and overcoming light leakage of pixels and color mixture occurring in an existing PDLC display device. The PDLC display device according to the present invention includes a PLDC substrate, an array substrate, and a QD substrate, having a simple structure, showing an innovated and unique displaying effect, demonstrating at least four displaying modes of red, green, blue, and indistinctness, and overcoming light leakage of pixels and color mixture occurring in an existing PDLC display device.