The invention discloses a solar illumination device which comprises a natural light collecting device. The top of the natural light collecting device is provided with an automatic cleaning device, a solar battery plate base recombiner is connected with the lower portion of the natural light collecting device in a buckled and sealed mode and is provided with multiple solar luminosity sensors, a reflection grating assembly is arranged on the inner wall of the solar battery plate base recombiner in a buckled mode, the lower end of the reflection grating assembly is fixedly provided with a light guide tube, a dimming device is arranged in the light guide tube, the dimming device is provided with a storage battery and a solar intelligent controller on the outer wall of the light guide tube, the storage battery is connected with a photovoltaic power generation assembly and the solar intelligent controller in the solar battery plate base recombiner through wires, the bottom end of the light guide tube is connected with a solar illumination device base, the bottom of the base is connected with a diffuser, and the base is provided with an LED illumination lamp set provided with an LED radiator in a matched mode. A natural light source is used for lighting and illumination during the day, photovoltaic power is combined with the LED lamp set for illumination at night, and accordingly the illumination requirements of use areas in a building are met.