The invention discloses a full-Stokes interference imaging spectral device and a method based on time-sharing polarization modulation. The full-Stokes interference imaging spectral device comprises a time-sharing polarization modulation device and a slit-free Sagnac interference imaging spectral device. The time-sharing polarization modulation device can be composed of a rotatable phase delayer and a fixed linear polarizer. The Sagnac interference imaging spectral device is composed of two imaging objective lens, a collimating objective lens, a Sagnac shear beam splitter, and an imaging detector. A target beam to be detected is incident on the time-sharing polarization modulation device to generate four different polarization states; after the target beam to be detected passes through the interference imaging spectral device, four groups of target images carrying different polarization state information and interference information are obtained on the target surface of the imaging detector; and through data processing, four-dimensional light information of a detection target scene is obtained ultimately, namely, two-dimensional spatial information, spectral information of each point, and full-Stokes polarization information of each spectrum. The full-Stokes interference imaging spectral device of the invention has the advantages of high luminous flux, high spatial resolution, and the like.