Abstract: An image display system and a signal synchronization device are provided. The image display system includes an image source, an image projection device and a liquid crystal shutter device. The image source is configured to provide an image signal and a first clock signal. The image projection device is connected to the image source and configured to generate an image projection light signal and a second clock signal according to the image signal and the first clock signal. The liquid crystal shutter device is disposed on a path of the image projection light signal and connected to the image source or the image projection device. The liquid crystal shutter device includes a plurality of liquid crystal molecules and is configured to control a light shading rate of the liquid crystal molecules according to phase changes of the first clock signal or the second clock signal.